diff --git a/wcfsetup/install/files/acp/update_com.woltlab.wcf_6.2_contactOptions.php b/wcfsetup/install/files/acp/update_com.woltlab.wcf_6.2_contactOptions.php
index 831b18cf09c..b3db104f01e 100644
--- a/wcfsetup/install/files/acp/update_com.woltlab.wcf_6.2_contactOptions.php
+++ b/wcfsetup/install/files/acp/update_com.woltlab.wcf_6.2_contactOptions.php
@@ -6,7 +6,7 @@
 
 use wcf\data\contact\option\ContactOptionEditor;
 use wcf\data\contact\option\ContactOptionList;
-use wcf\util\JSON;
+
 use wcf\util\OptionUtil;
 
 $contactOptionList = new ContactOptionList();
@@ -39,7 +39,7 @@
     $editor = new ContactOptionEditor($contactOption);
     $editor->update([
         'optionType' => $optionType,
-        'configuration' => JSON::encode($configuration),
+        'configuration' => \json_encode($configuration, \JSON_THROW_ON_ERROR),
     ]);
 }
 
@@ -57,5 +57,5 @@ function convertSelectOptions(string $selectOptions): string
         ];
     }
 
-    return JSON::encode($options);
+    return \json_encode($options, \JSON_THROW_ON_ERROR);
 }
diff --git a/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php b/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
index f72c6d4d582..860835dd16c 100644
--- a/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
+++ b/wcfsetup/install/files/lib/acp/action/WorkerProxyAction.class.php
@@ -8,7 +8,6 @@
 use wcf\system\exception\SystemException;
 use wcf\system\WCF;
 use wcf\system\worker\IWorker;
-use wcf\util\JSON;
 
 /**
  * Handles worker actions.
@@ -143,7 +142,7 @@ protected function sendResponse($progress = 0, ?array $parameters = null, $proce
 
         // send JSON-encoded response
         \header('Content-type: application/json; charset=UTF-8');
-        echo JSON::encode($returnValues);
+        echo \json_encode($returnValues, \JSON_THROW_ON_ERROR);
 
         exit;
     }
diff --git a/wcfsetup/install/files/lib/acp/form/AbstractFormOptionAddForm.class.php b/wcfsetup/install/files/lib/acp/form/AbstractFormOptionAddForm.class.php
index 917e6870f15..79a73afbe9f 100644
--- a/wcfsetup/install/files/lib/acp/form/AbstractFormOptionAddForm.class.php
+++ b/wcfsetup/install/files/lib/acp/form/AbstractFormOptionAddForm.class.php
@@ -12,7 +12,6 @@
 use wcf\system\form\builder\IFormDocument;
 use wcf\system\form\option\FormOptionHandler;
 use wcf\system\form\option\SharedConfigurationFormFields;
-use wcf\util\JSON;
 
 /**
  * Default implementation for a form that adds custom options based on the form option system.
@@ -47,7 +46,7 @@ function (IFormDocument $document, array $parameters) {
                         }
                     }
 
-                    $parameters['data']['configuration'] = JSON::encode($configuration);
+                    $parameters['data']['configuration'] = \json_encode($configuration, \JSON_THROW_ON_ERROR);
 
                     return $parameters;
                 },
@@ -56,7 +55,7 @@ function (IFormDocument $document, array $data, IStorableObject $object) {
 
                     // @phpstan-ignore property.notFound
                     if ($object->configuration) {
-                        $data = \array_merge($data, JSON::decode($object->configuration));
+                        $data = \array_merge($data, \json_decode($object->configuration, true, flags: \JSON_THROW_ON_ERROR));
                     }
 
                     return $data;
diff --git a/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php b/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
index eb62ecb3a48..951132bbe85 100644
--- a/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXFileDeleteAction.class.php
@@ -6,7 +6,6 @@
 use wcf\system\exception\UserInputException;
 use wcf\system\file\upload\UploadFile;
 use wcf\system\file\upload\UploadHandler;
-use wcf\util\JSON;
 
 /**
  * Copy of the default implementation for file uploads using the AJAX-API.
@@ -97,7 +96,7 @@ public function execute()
      */
     protected function sendJsonResponse(array $data)
     {
-        $json = JSON::encode($data);
+        $json = \json_encode($data, \JSON_THROW_ON_ERROR);
 
         // send JSON response
         \header('Content-type: application/json; charset=UTF-8');
diff --git a/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php b/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
index 41abe4c9f05..e78bd26b51a 100644
--- a/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXFileUploadAction.class.php
@@ -9,7 +9,6 @@
 use wcf\system\WCF;
 use wcf\util\FileUtil;
 use wcf\util\ImageUtil;
-use wcf\util\JSON;
 
 /**
  * Copy of the default implementation for file uploads using the AJAX-API.
@@ -153,7 +152,7 @@ public function execute()
      */
     protected function sendJsonResponse(array $data)
     {
-        $json = JSON::encode($data);
+        $json = \json_encode($data, \JSON_THROW_ON_ERROR);
 
         // send JSON response
         \header('Content-type: application/json; charset=UTF-8');
diff --git a/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php b/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
index ea065c757c4..af95241664c 100644
--- a/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
+++ b/wcfsetup/install/files/lib/action/AJAXInvokeAction.class.php
@@ -11,7 +11,6 @@
 use wcf\system\IAJAXInvokeAction;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -168,7 +167,7 @@ protected function invoke()
     protected function sendResponse()
     {
         \header('Content-type: application/json; charset=UTF-8');
-        echo JSON::encode($this->response);
+        echo \json_encode($this->response, \JSON_THROW_ON_ERROR);
 
         exit;
     }
diff --git a/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php b/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
index 4452a35525a..3631890b10b 100644
--- a/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractAjaxAction.class.php
@@ -2,8 +2,6 @@
 
 namespace wcf\action;
 
-use wcf\util\JSON;
-
 /**
  * @deprecated 5.5 Use PSR-7 responses (e.g. Laminas' JsonResponse).
  */
@@ -17,7 +15,7 @@ abstract class AbstractAjaxAction extends AbstractAction
      */
     protected function sendJsonResponse(array $data)
     {
-        $json = JSON::encode($data);
+        $json = \json_encode($data, \JSON_THROW_ON_ERROR);
 
         // send JSON response
         \header('Content-type: application/json; charset=UTF-8');
diff --git a/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php b/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
index fead01ebd89..35651a6e108 100644
--- a/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractOauth2Action.class.php
@@ -17,7 +17,6 @@
 use wcf\system\user\authentication\oauth\User as OauthUser;
 use wcf\system\WCF;
 use wcf\util\HtmlString;
-use wcf\util\JSON;
 
 /**
  * Generic implementation to handle the OAuth 2 flow.
@@ -182,7 +181,7 @@ protected function codeToAccessToken(string $code): array
             }
         }
 
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
         if (!empty($parsed['error'])) {
             throw new \Exception(\sprintf(
diff --git a/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php b/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
index 484946f7e41..f793c0ca011 100644
--- a/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/AbstractOauth2AuthAction.class.php
@@ -30,7 +30,6 @@
 use wcf\system\user\authentication\oauth\User as OauthUser;
 use wcf\system\WCF;
 use wcf\util\HtmlString;
-use wcf\util\JSON;
 
 /**
  * Generic implementation to handle the OAuth 2 flow.
@@ -163,7 +162,7 @@ protected function getAccessToken(OAuth2Success $auth2Success): array
             }
         }
 
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
         if (!empty($parsed['error'])) {
             throw new \Exception(
diff --git a/wcfsetup/install/files/lib/action/FacebookAuthAction.class.php b/wcfsetup/install/files/lib/action/FacebookAuthAction.class.php
index f61ddcfaff8..546bbca4ce6 100644
--- a/wcfsetup/install/files/lib/action/FacebookAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/FacebookAuthAction.class.php
@@ -5,7 +5,6 @@
 use GuzzleHttp\Psr7\Request;
 use wcf\system\request\LinkHandler;
 use wcf\system\user\authentication\oauth\User as OauthUser;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -75,7 +74,7 @@ protected function getUser(array $accessToken): OauthUser
             'authorization' => \sprintf('Bearer %s', $accessToken['access_token']),
         ]);
         $response = $this->getHttpClient()->send($request);
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
         $parsed['__id'] = $parsed['id'];
         $parsed['__username'] = $parsed['name'];
diff --git a/wcfsetup/install/files/lib/action/GithubAuthAction.class.php b/wcfsetup/install/files/lib/action/GithubAuthAction.class.php
index d22c60745c5..0e40e6846ee 100644
--- a/wcfsetup/install/files/lib/action/GithubAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/GithubAuthAction.class.php
@@ -7,7 +7,6 @@
 use Psr\Http\Message\ResponseInterface;
 use wcf\system\request\LinkHandler;
 use wcf\system\user\authentication\oauth\User as OauthUser;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -71,7 +70,7 @@ protected function getUser(array $accessToken): OauthUser
             'authorization' => \sprintf('Bearer %s', $accessToken['access_token']),
         ]);
         $response = $this->getHttpClient()->send($request);
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
         $parsed['__id'] = $parsed['id'];
         $parsed['__username'] = $parsed['login'];
@@ -95,7 +94,7 @@ protected function redirectToRegistration(OauthUser $oauthUser): ResponseInterfa
                 'authorization' => \sprintf('Bearer %s', $oauthUser["accessToken"]["access_token"]),
             ]);
             $response = $this->getHttpClient()->send($request);
-            $emails = JSON::decode((string)$response->getBody());
+            $emails = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
             // search primary email
             $email = $emails[0]['email'];
diff --git a/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php b/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
index e2b8de754d3..d2a50a33b42 100644
--- a/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/GoogleAuthAction.class.php
@@ -5,7 +5,6 @@
 use GuzzleHttp\Psr7\Request;
 use wcf\system\request\LinkHandler;
 use wcf\system\user\authentication\oauth\User as OauthUser;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -35,7 +34,7 @@ private function getConfiguration(): array
             $request = new Request('GET', 'https://accounts.google.com/.well-known/openid-configuration');
             $response = $this->getHttpClient()->send($request);
 
-            $this->configuration = JSON::decode((string)$response->getBody());
+            $this->configuration = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
         }
 
         return $this->configuration;
@@ -91,7 +90,7 @@ protected function getUser(array $accessToken): OauthUser
             'authorization' => \sprintf('Bearer %s', $accessToken['access_token']),
         ]);
         $response = $this->getHttpClient()->send($request);
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
         $parsed['__id'] = $parsed['sub'];
         $parsed['__username'] = $parsed['name'];
diff --git a/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php b/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
index c0512bc43eb..5c89139c0af 100644
--- a/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
+++ b/wcfsetup/install/files/lib/action/TwitterAuthAction.class.php
@@ -17,7 +17,6 @@
 use wcf\system\user\authentication\oauth\twitter\Success as OAuth2TwitterSuccess;
 use wcf\system\user\authentication\oauth\User as OauthUser;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -134,7 +133,7 @@ protected function getUser(array $accessToken): OauthUser
         );
         $response = $this->getHttpClient()->send($request);
 
-        $parsed = JSON::decode((string)$response->getBody());
+        $parsed = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
         $parsed['__id'] = $parsed['id'];
         $parsed['__username'] = $parsed['name'];
         if (!empty($parsed['email'])) {
diff --git a/wcfsetup/install/files/lib/command/style/CreateManifest.class.php b/wcfsetup/install/files/lib/command/style/CreateManifest.class.php
index a8574f7015b..b4fd71c8f27 100644
--- a/wcfsetup/install/files/lib/command/style/CreateManifest.class.php
+++ b/wcfsetup/install/files/lib/command/style/CreateManifest.class.php
@@ -7,7 +7,6 @@
 use wcf\system\io\AtomicWriter;
 use wcf\system\language\LanguageFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Generate then `manifest-*.json` files for a style.
@@ -43,7 +42,7 @@ public function __invoke(): void
                 "type" => "image/png"
             ];
         }
-        $icons = JSON::encode($icons);
+        $icons = \json_encode($icons, \JSON_THROW_ON_ERROR);
 
         $originalLanguage = WCF::getLanguage();
         try {
@@ -51,8 +50,8 @@ public function __invoke(): void
                 // To get the correct landing page url, we need to change the language.
                 WCF::setLanguage($language->languageID);
 
-                $title = JSON::encode($language->get(PAGE_TITLE));
-                $startUrl = JSON::encode($landingPage->getLink());
+                $title = \json_encode($language->get(PAGE_TITLE), \JSON_THROW_ON_ERROR);
+                $startUrl = \json_encode($landingPage->getLink(), \JSON_THROW_ON_ERROR);
 
                 // update manifest.json
                 $manifest = <<<MANIFEST
diff --git a/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php b/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
index 723550d8e51..6e73e2e0656 100644
--- a/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
+++ b/wcfsetup/install/files/lib/data/AbstractDatabaseObjectAction.class.php
@@ -9,7 +9,6 @@
 use wcf\system\request\RequestHandler;
 use wcf\system\WCF;
 use wcf\util\ArrayUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -655,8 +654,8 @@ protected function readValue($variableName, $allowEmpty, $arrayIndex, $type, $st
                     }
                 } else {
                     try {
-                        $target[$variableName] = JSON::decode($target[$variableName]);
-                    } catch (SystemException $e) {
+                        $target[$variableName] = \json_decode($target[$variableName], true, flags: \JSON_THROW_ON_ERROR);
+                    } catch (\JsonException) {
                         throw new UserInputException($variableName);
                     }
 
diff --git a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
index 8d8817df4cd..31dd8f304e2 100644
--- a/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/entry/BlacklistEntryAction.class.php
@@ -9,7 +9,6 @@
 use wcf\data\blacklist\status\BlacklistStatusEditor;
 use wcf\system\io\HttpFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Executes blacklist entry-related actions.
@@ -61,7 +60,7 @@ public function import()
             return;
         }
 
-        $data = JSON::decode((string)$response->getBody());
+        $data = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
         $sql = "INSERT INTO             wcf1_blacklist_entry
                                         (type, hash, lastSeen, occurrences)
                 VALUES                  (?, ?, ?, ?)
diff --git a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatus.class.php b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatus.class.php
index a157ae2fb20..f1fe715a805 100644
--- a/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatus.class.php
+++ b/wcfsetup/install/files/lib/data/blacklist/status/BlacklistStatus.class.php
@@ -8,7 +8,6 @@
 use wcf\data\DatabaseObject;
 use wcf\system\exception\SystemException;
 use wcf\system\io\HttpFactory;
-use wcf\util\JSON;
 
 /**
  * Represents a blacklist status.
@@ -113,7 +112,7 @@ public static function getNextDelta(array $status, ?ClientInterface $client = nu
             return null;
         }
 
-        $data = JSON::decode((string)$response->getBody());
+        $data = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
         $deltas = ['delta1', 'delta2', 'delta3', 'delta4'];
 
         // The array is ordered from "now" to "14 days ago".
diff --git a/wcfsetup/install/files/lib/data/contact/option/ContactOption.class.php b/wcfsetup/install/files/lib/data/contact/option/ContactOption.class.php
index 75ea37865a8..6a7abb82034 100644
--- a/wcfsetup/install/files/lib/data/contact/option/ContactOption.class.php
+++ b/wcfsetup/install/files/lib/data/contact/option/ContactOption.class.php
@@ -8,7 +8,6 @@
 use wcf\system\form\option\FormOptionHandler;
 use wcf\system\form\option\IFormOption;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Represents a contact option.
@@ -75,6 +74,6 @@ public function getFormOption(): IFormOption
      */
     public function getConfiguration(): array
     {
-        return $this->configuration ? JSON::decode($this->configuration) : [];
+        return $this->configuration ? \json_decode($this->configuration, true, flags: \JSON_THROW_ON_ERROR) : [];
     }
 }
diff --git a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItem.class.php b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItem.class.php
index 05922816fdc..d419fd41ed2 100644
--- a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItem.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItem.class.php
@@ -6,7 +6,6 @@
 use wcf\data\language\Language;
 use wcf\system\language\LanguageFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Represents a missing language item log entry.
@@ -47,7 +46,7 @@ public function getLanguage()
      */
     public function getStackTrace()
     {
-        $stackTrace = JSON::decode($this->stackTrace);
+        $stackTrace = \json_decode($this->stackTrace, true, flags: \JSON_THROW_ON_ERROR);
 
         return WCF::getTPL()->render('wcf', '__devtoolsMissingLanguageItemStackTrace', [
             'stackTrace' => $stackTrace,
diff --git a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
index d9bcd8c90ae..68173109515 100644
--- a/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
+++ b/wcfsetup/install/files/lib/data/devtools/missing/language/item/DevtoolsMissingLanguageItemAction.class.php
@@ -6,7 +6,6 @@
 use wcf\data\IDeleteAction;
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -70,7 +69,7 @@ public function logLanguageItem()
             return $item;
         }, \wcf\functions\exception\sanitizeStacktrace(new \Exception(), true));
 
-        $stackTrace = JSON::encode($stackTraceData);
+        $stackTrace = \json_encode($stackTraceData, \JSON_THROW_ON_ERROR);
 
         $sql = "INSERT INTO             wcf1_devtools_missing_language_item
                                         (languageID, languageItem, lastTime, stackTrace)
diff --git a/wcfsetup/install/files/lib/data/file/File.class.php b/wcfsetup/install/files/lib/data/file/File.class.php
index 3b4a04759d2..86b748ef10b 100644
--- a/wcfsetup/install/files/lib/data/file/File.class.php
+++ b/wcfsetup/install/files/lib/data/file/File.class.php
@@ -12,7 +12,6 @@
 use wcf\system\file\processor\IImageDataProvider;
 use wcf\system\file\processor\ImageData;
 use wcf\system\request\LinkHandler;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -220,8 +219,8 @@ public function toHtmlElement(?array $metaData = null): string
             StringUtil::encodeHTML($this->filename),
             $this->fileSize,
             StringUtil::encodeHTML($this->mimeType),
-            StringUtil::encodeHTML(JSON::encode($thumbnails)),
-            $metaData === null ? "" : 'data-meta-data="' . StringUtil::encodeHTML(JSON::encode($metaData)) . '"',
+            StringUtil::encodeHTML(\json_encode($thumbnails, \JSON_THROW_ON_ERROR)),
+            $metaData === null ? "" : 'data-meta-data="' . StringUtil::encodeHTML(\json_encode($metaData, \JSON_THROW_ON_ERROR)) . '"',
             StringUtil::encodeHTML($this->getLink()),
         );
     }
diff --git a/wcfsetup/install/files/lib/data/file/FileEditor.class.php b/wcfsetup/install/files/lib/data/file/FileEditor.class.php
index d0df7b5398a..cdc5087971f 100644
--- a/wcfsetup/install/files/lib/data/file/FileEditor.class.php
+++ b/wcfsetup/install/files/lib/data/file/FileEditor.class.php
@@ -11,7 +11,6 @@
 use wcf\system\image\ImageHandler;
 use wcf\util\ExifUtil;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 
 /**
  * @author Alexander Ebert
diff --git a/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php b/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
index 98f41099094..99836c1ad58 100644
--- a/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
+++ b/wcfsetup/install/files/lib/data/file/temporary/FileTemporary.class.php
@@ -4,7 +4,6 @@
 
 use wcf\data\DatabaseObject;
 use wcf\system\file\processor\FileProcessor;
-use wcf\util\JSON;
 
 /**
  * @author Alexander Ebert
@@ -80,7 +79,7 @@ public function getPathname(): string
      */
     public function getContext(): array
     {
-        return JSON::decode($this->context);
+        return \json_decode($this->context, true, flags: \JSON_THROW_ON_ERROR);
     }
 
     public static function getNumberOfChunks(int $fileSize): int
diff --git a/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php b/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
index db0a6b26a85..89cbb8e8b60 100644
--- a/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
+++ b/wcfsetup/install/files/lib/data/like/object/LikeObject.class.php
@@ -7,7 +7,6 @@
 use wcf\data\reaction\type\ReactionTypeCache;
 use wcf\data\user\User;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Represents a liked object.
@@ -98,7 +97,7 @@ protected function handleData($data)
                         $this->reactions[$reactionTypeID] = [
                             'reactionCount' => $reactionCount,
                             'renderedReactionIcon' => $reactionType->renderIcon(),
-                            'renderedReactionIconEncoded' => JSON::encode($reactionType->renderIcon()),
+                            'renderedReactionIconEncoded' => \json_encode($reactionType->renderIcon(), \JSON_THROW_ON_ERROR),
                             'reactionTitle' => $reactionType->getTitle(),
                         ];
                     }
@@ -178,7 +177,7 @@ public function getReactionsJson(): string
             ];
         }
 
-        return JSON::encode($data);
+        return \json_encode($data, \JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/data/user/User.class.php b/wcfsetup/install/files/lib/data/user/User.class.php
index 84cac1eee3f..fca14c0480a 100644
--- a/wcfsetup/install/files/lib/data/user/User.class.php
+++ b/wcfsetup/install/files/lib/data/user/User.class.php
@@ -16,7 +16,6 @@
 use wcf\system\user\authentication\password\PasswordAlgorithmManager;
 use wcf\system\user\storage\UserStorageHandler;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\UserUtil;
 
 /**
@@ -660,7 +659,7 @@ public function canPurchasePaidSubscriptions()
     public function getBlacklistMatches()
     {
         if ($this->pendingActivation() && $this->blacklistMatches) {
-            return JSON::decode($this->blacklistMatches);
+            return \json_decode($this->blacklistMatches, true, flags: \JSON_THROW_ON_ERROR);
         }
 
         return [];
diff --git a/wcfsetup/install/files/lib/form/AccountManagementForm.class.php b/wcfsetup/install/files/lib/form/AccountManagementForm.class.php
index c154bfe5c3e..fd9fcd92e05 100644
--- a/wcfsetup/install/files/lib/form/AccountManagementForm.class.php
+++ b/wcfsetup/install/files/lib/form/AccountManagementForm.class.php
@@ -9,12 +9,10 @@
 use wcf\system\email\mime\MimePartFacade;
 use wcf\system\email\mime\RecipientAwareTextMimePart;
 use wcf\system\email\UserMailbox;
-use wcf\system\exception\SystemException;
 use wcf\system\exception\UserInputException;
 use wcf\system\menu\user\UserMenu;
 use wcf\system\user\authentication\configuration\UserAuthenticationConfigurationFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use wcf\util\UserRegistrationUtil;
 
@@ -155,8 +153,8 @@ public function readFormParameters()
         }
         if (isset($_POST['newPassword_passwordStrengthVerdict'])) {
             try {
-                $this->newPasswordStrengthVerdict = JSON::decode($_POST['newPassword_passwordStrengthVerdict']);
-            } catch (SystemException $e) {
+                $this->newPasswordStrengthVerdict = \json_decode($_POST['newPassword_passwordStrengthVerdict'], true, flags: \JSON_THROW_ON_ERROR);
+            } catch (\JsonException) {
                 // ignore
             }
         }
diff --git a/wcfsetup/install/files/lib/form/NewPasswordForm.class.php b/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
index ecc4acb8874..5dbc780d8e4 100644
--- a/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
+++ b/wcfsetup/install/files/lib/form/NewPasswordForm.class.php
@@ -7,7 +7,6 @@
 use wcf\system\exception\IllegalLinkException;
 use wcf\system\exception\NamedUserException;
 use wcf\system\exception\PermissionDeniedException;
-use wcf\system\exception\SystemException;
 use wcf\system\form\builder\container\FormContainer;
 use wcf\system\form\builder\field\PasswordFormField;
 use wcf\system\form\builder\field\validation\FormFieldValidationError;
@@ -17,7 +16,6 @@
 use wcf\system\WCF;
 use wcf\util\HeaderUtil;
 use wcf\util\HtmlString;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use wcf\util\UserRegistrationUtil;
 
@@ -120,8 +118,8 @@ private function validatePassword(PasswordFormField $formField): void
     {
         if (isset($_POST['newPassword_passwordStrengthVerdict'])) {
             try {
-                $newPasswordStrengthVerdict = JSON::decode($_POST['newPassword_passwordStrengthVerdict']);
-            } catch (SystemException $e) {
+                $newPasswordStrengthVerdict = \json_decode($_POST['newPassword_passwordStrengthVerdict'], true, flags: \JSON_THROW_ON_ERROR);
+            } catch (\JsonException) {
                 // ignore
             }
         }
diff --git a/wcfsetup/install/files/lib/form/RegisterForm.class.php b/wcfsetup/install/files/lib/form/RegisterForm.class.php
index fc8955d22cd..1a945a2e950 100644
--- a/wcfsetup/install/files/lib/form/RegisterForm.class.php
+++ b/wcfsetup/install/files/lib/form/RegisterForm.class.php
@@ -29,7 +29,6 @@
 use wcf\system\WCF;
 use wcf\util\HeaderUtil;
 use wcf\util\HtmlString;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use wcf\util\UserRegistrationUtil;
 use wcf\util\UserUtil;
@@ -169,10 +168,12 @@ public function readFormParameters()
         }
         if (isset($_POST[$this->randomFieldNames['password'] . '_passwordStrengthVerdict'])) {
             try {
-                $this->passwordStrengthVerdict = JSON::decode(
-                    $_POST[$this->randomFieldNames['password'] . '_passwordStrengthVerdict']
+                $this->passwordStrengthVerdict = \json_decode(
+                    $_POST[$this->randomFieldNames['password'] . '_passwordStrengthVerdict'],
+                    true,
+                    flags: \JSON_THROW_ON_ERROR
                 );
-            } catch (SystemException $e) {
+            } catch (\JsonException) {
                 // ignore
             }
         }
@@ -429,7 +430,7 @@ public function save()
                 'username' => $this->username,
                 'email' => $this->email,
                 'password' => $this->password,
-                'blacklistMatches' => $this->spamCheckEvent->hasMatches() ? JSON::encode($this->spamCheckEvent->getMatches()) : '',
+                'blacklistMatches' => $this->spamCheckEvent->hasMatches() ? \json_encode($this->spamCheckEvent->getMatches(), \JSON_THROW_ON_ERROR) : '',
                 'signatureEnableHtml' => 1,
             ]),
             'groups' => $this->groupIDs,
diff --git a/wcfsetup/install/files/lib/http/middleware/JsonBody.class.php b/wcfsetup/install/files/lib/http/middleware/JsonBody.class.php
index e8514852fbb..f1cc8282f9b 100644
--- a/wcfsetup/install/files/lib/http/middleware/JsonBody.class.php
+++ b/wcfsetup/install/files/lib/http/middleware/JsonBody.class.php
@@ -8,8 +8,6 @@
 use Psr\Http\Message\ServerRequestInterface;
 use Psr\Http\Server\MiddlewareInterface;
 use Psr\Http\Server\RequestHandlerInterface;
-use wcf\system\exception\SystemException;
-use wcf\util\JSON;
 
 /**
  * Decodes requests containing a JSON body.
@@ -31,8 +29,8 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         $hasValidJson = false;
         if ($this->contentTypeIsJson($request)) {
             try {
-                $data = JSON::decode($request->getBody());
-            } catch (SystemException $e) {
+                $data = \json_decode($request->getBody(), true, flags: \JSON_THROW_ON_ERROR);
+            } catch (\JsonException) {
                 return new TextResponse('Failed to decode the request body.', 400);
             }
 
diff --git a/wcfsetup/install/files/lib/system/CLIWCF.class.php b/wcfsetup/install/files/lib/system/CLIWCF.class.php
index ed9d2896997..27a4bfbdad7 100644
--- a/wcfsetup/install/files/lib/system/CLIWCF.class.php
+++ b/wcfsetup/install/files/lib/system/CLIWCF.class.php
@@ -13,7 +13,6 @@
 use wcf\system\exception\UserInputException;
 use wcf\system\user\authentication\UserAuthenticationFactory;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use Zend\Console\Exception\RuntimeException as ArgvException;
 use Zend\Console\Getopt as ArgvParser;
@@ -285,7 +284,7 @@ protected function initCommands(): void
                 $command = CLICommandHandler::getCommand($line);
                 $command->execute(CLICommandHandler::getParameters($line));
             } catch (IllegalLinkException $e) {
-                Log::error('notFound:' . JSON::encode(['command' => $line]));
+                Log::error('notFound:' . \json_encode(['command' => $line], \JSON_THROW_ON_ERROR));
                 self::getReader()->println(WCF::getLanguage()->getDynamicVariable(
                     'wcf.cli.error.command.notFound',
                     ['command' => $line]
diff --git a/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php b/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
index 459e062758f..d3d065e566f 100644
--- a/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
+++ b/wcfsetup/install/files/lib/system/acl/ACLHandler.class.php
@@ -15,7 +15,6 @@
 use wcf\system\exception\SystemException;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Handles ACL permissions.
@@ -81,7 +80,7 @@ public function assignVariables($objectTypeID)
 
             $users = [];
             foreach ($values as $type => $optionData) {
-                $optionData = JSON::decode($optionData);
+                $optionData = \json_decode($optionData, true, flags: \JSON_THROW_ON_ERROR);
                 if ($type === 'user') {
                     $users = User::getUsers(\array_keys($optionData));
                 }
@@ -167,7 +166,7 @@ public function readValues($objectTypeID, ?array $valuesSource = null)
                 if (isset($valuesSource[$type])) {
                     $this->__readValues[$objectTypeID][$type] = [];
 
-                    foreach (JSON::decode($valuesSource[$type]) as $typeID => $optionData) {
+                    foreach (\json_decode($valuesSource[$type], true, flags: \JSON_THROW_ON_ERROR) as $typeID => $optionData) {
                         $this->__readValues[$objectTypeID][$type][$typeID] = [];
 
                         foreach ($optionData as $optionID => $optionValue) {
@@ -177,7 +176,7 @@ public function readValues($objectTypeID, ?array $valuesSource = null)
                         }
                     }
 
-                    $this->__readValues[$objectTypeID][$type] = JSON::encode($this->__readValues[$objectTypeID][$type]);
+                    $this->__readValues[$objectTypeID][$type] = \json_encode($this->__readValues[$objectTypeID][$type], \JSON_THROW_ON_ERROR);
                 }
             }
         }
@@ -282,9 +281,9 @@ protected function replaceValues(ACLOptionList $optionList, $type, $objectID)
         // add new values if given
         $values = [];
         if (isset($this->__readValues[$objectTypeID]) && isset($this->__readValues[$objectTypeID][$type])) {
-            $values = JSON::decode($this->__readValues[$objectTypeID][$type]);
+            $values = \json_decode($this->__readValues[$objectTypeID][$type], true, flags: \JSON_THROW_ON_ERROR);
         } elseif (isset($_POST['aclValues']) && isset($_POST['aclValues'][$type])) {
-            $values = JSON::decode($_POST['aclValues'][$type]);
+            $values = \json_decode($_POST['aclValues'][$type], true, flags: \JSON_THROW_ON_ERROR);
         }
 
         $sql = "INSERT INTO wcf1_acl_option_to_" . $type . "
diff --git a/wcfsetup/install/files/lib/system/background/job/ServiceWorkerDeliveryBackgroundJob.class.php b/wcfsetup/install/files/lib/system/background/job/ServiceWorkerDeliveryBackgroundJob.class.php
index b80c5637f73..0dac0211aad 100644
--- a/wcfsetup/install/files/lib/system/background/job/ServiceWorkerDeliveryBackgroundJob.class.php
+++ b/wcfsetup/install/files/lib/system/background/job/ServiceWorkerDeliveryBackgroundJob.class.php
@@ -13,7 +13,6 @@
 use wcf\system\style\StyleHandler;
 use wcf\system\user\notification\UserNotificationHandler;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -114,7 +113,7 @@ private function sendNotification(int $serviceWorkerID, int $notificationID): vo
                 "icon" => $style->getFaviconAppleTouchIcon(),
             ];
 
-            $report = ServiceWorkerHandler::getInstance()->sendOneNotification($serviceWorker, JSON::encode($content));
+            $report = ServiceWorkerHandler::getInstance()->sendOneNotification($serviceWorker, \json_encode($content, \JSON_THROW_ON_ERROR));
             if (!$report->isSuccess()) {
                 (new ServiceWorkerEditor($serviceWorker))->delete();
             }
diff --git a/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php b/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
index df3abdd89fc..6b10bcd0cd7 100644
--- a/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/BBCodeHandler.class.php
@@ -9,7 +9,6 @@
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
 use wcf\util\ArrayUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -161,11 +160,11 @@ public function getSourceBBCodes()
     public function getHighlighterMeta()
     {
         if ($this->highlighterMeta === null) {
-            $this->highlighterMeta = JSON::decode(\preg_replace(
+            $this->highlighterMeta = \json_decode(\preg_replace(
                 '/.*\/\*!START\*\/\s*const\s*metadata\s*=\s*(.*)\s*;\s*\/\*!END\*\/.*/s',
                 '\\1',
                 \file_get_contents(WCF_DIR . 'js/WoltLabSuite/Core/prism-meta.js')
-            ));
+            ), true, flags: \JSON_THROW_ON_ERROR);
         }
 
         return $this->highlighterMeta;
diff --git a/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
index 616e6c78b9e..9e3b5ad91ab 100644
--- a/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/DomBBCodeParser.class.php
@@ -4,7 +4,6 @@
 
 use wcf\data\bbcode\BBCodeCache;
 use wcf\system\SingletonFactory;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -146,12 +145,12 @@ public function parse(\DOMDocument $document): void
             }
 
             if ($node->hasAttribute('data-attributes')) {
-                $attributes = JSON::decode(\base64_decode($node->getAttribute('data-attributes')));
+                $attributes = \json_decode(\base64_decode($node->getAttribute('data-attributes')), true, flags: \JSON_THROW_ON_ERROR);
             } else {
                 $attributes = [];
             }
             $attributes[$attributeNo] = $text;
-            $node->setAttribute('data-attributes', \base64_encode(JSON::encode($attributes)));
+            $node->setAttribute('data-attributes', \base64_encode(\json_encode($attributes, \JSON_THROW_ON_ERROR)));
         }
         foreach ($nodes as $node) {
             $node->parentNode?->removeChild($node);
@@ -258,13 +257,13 @@ private function createMetacodeMarker(string $bbcodeTag): ?\DOMElement
             if ($attributes !== []) {
                 $metacodeMarker->setAttribute(
                     'data-attributes',
-                    \base64_encode(JSON::encode(\array_map(static function ($attribute) {
+                    \base64_encode(\json_encode(\array_map(static function ($attribute) {
                         if (\preg_match('~^([\'"])(?P<content>.*)(\1)$~', $attribute, $matches)) {
                             return $matches['content'];
                         }
 
                         return $attribute;
-                    }, $attributes)))
+                    }, $attributes), \JSON_THROW_ON_ERROR))
                 );
             }
         }
diff --git a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
index 1e5c443ff7d..0865c818ba6 100644
--- a/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
+++ b/wcfsetup/install/files/lib/system/bbcode/HtmlBBCodeParser.class.php
@@ -5,7 +5,6 @@
 use wcf\data\bbcode\attribute\BBCodeAttribute;
 use wcf\system\exception\SystemException;
 use wcf\util\DOMUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -435,7 +434,7 @@ protected function buildOpeningTag(array $tag)
             }, $tag['attributes']);
 
             // uses base64 encoding to avoid an "escape" nightmare
-            $attributes = ' data-attributes="' . \base64_encode(JSON::encode($tag['attributes'])) . '"';
+            $attributes = ' data-attributes="' . \base64_encode(\json_encode($tag['attributes'], \JSON_THROW_ON_ERROR)) . '"';
 
             if (isset($tag['useText'])) {
                 $attributes .= ' data-use-text="' . $tag['useText'] . '"';
diff --git a/wcfsetup/install/files/lib/system/captcha/RecaptchaHandler.class.php b/wcfsetup/install/files/lib/system/captcha/RecaptchaHandler.class.php
index 78134d28858..5b46b5eb7ac 100644
--- a/wcfsetup/install/files/lib/system/captcha/RecaptchaHandler.class.php
+++ b/wcfsetup/install/files/lib/system/captcha/RecaptchaHandler.class.php
@@ -8,7 +8,6 @@
 use wcf\system\exception\UserInputException;
 use wcf\system\io\HttpFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\UserUtil;
 
 /**
@@ -136,7 +135,7 @@ public function validate()
 
         try {
             $response = $this->getHttpClient()->send($request);
-            $data = JSON::decode((string)$response->getBody());
+            $data = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
             if ($data['success']) {
                 // reCaptcha v3 score ranges from 1.0(very likely a good interaction) and 0.0(very likely a bot),
diff --git a/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php b/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
index 7ddea25c8dd..d406813b2f1 100644
--- a/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
+++ b/wcfsetup/install/files/lib/system/cli/command/WorkerCLICommand.class.php
@@ -12,7 +12,6 @@
 use wcf\system\worker\IWorker;
 use wcf\util\CLIUtil;
 use wcf\util\DirectoryUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use Zend\Console\Exception\RuntimeException as ArgvException;
 use Zend\Console\Getopt as ArgvParser;
@@ -171,25 +170,25 @@ public function execute(array $parameters)
                 $progress = $worker->getProgress();
                 $progressbar->update($progress);
                 if ($output) {
-                    $output->write(JSON::encode([
+                    $output->write(\json_encode([
                         'iteration' => $i,
                         'progress' => $progress,
-                    ]) . "\n");
+                    ], \JSON_THROW_ON_ERROR) . "\n");
                 }
             }
         } catch (\Exception $e) {
             if ($output) {
-                $output->write(JSON::encode([
+                $output->write(\json_encode([
                     'error' => (string)$e,
-                ]));
+                ], \JSON_THROW_ON_ERROR));
             }
             throw $e;
         }
         if ($output) {
-            $output->write(JSON::encode([
+            $output->write(\json_encode([
                 'finished' => true,
                 'progress' => $progress,
-            ]) . "\n");
+            ], \JSON_THROW_ON_ERROR) . "\n");
             $output->close();
         }
         $progressbar->update($progress);
@@ -324,7 +323,7 @@ protected function spawnController(IWorker $worker, $threads)
                     $statusPrefix = 'T' . $processData['threadId'] . ': ';
                     if ($line) {
                         // If a line could be read we update the progressbar with the data sent.
-                        $parsedLine = JSON::decode(StringUtil::trim($line));
+                        $parsedLine = \json_decode(StringUtil::trim($line), true, flags: \JSON_THROW_ON_ERROR);
 
                         if (!empty($parsedLine['error'])) {
                             \fwrite(\STDERR, \str_repeat("\n", -$cursorOffset + 1));
diff --git a/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php b/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
index 1b856186a30..ace3bc8665d 100644
--- a/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/DevtoolsSetup.class.php
@@ -4,7 +4,6 @@
 
 use wcf\system\SingletonFactory;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 
 /**
  * Enables the rapid deployment of new installations using a central configuration file
@@ -71,7 +70,7 @@ protected function init()
         $contents = \file_get_contents($docRoot . self::CONFIGURATION_FILE);
 
         // allow the exception to go rampage
-        $this->configuration = JSON::decode($contents);
+        $this->configuration = \json_decode($contents, true, flags: \JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
index 46dac0918de..abfa092af9d 100644
--- a/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
+++ b/wcfsetup/install/files/lib/system/devtools/pip/DevtoolsPip.class.php
@@ -10,7 +10,6 @@
 use wcf\system\package\plugin\IPackageInstallationPlugin;
 use wcf\system\WCF;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 
 /**
  * Wrapper class for package installation plugins for use with the sync feature.
@@ -114,7 +113,7 @@ public function getSyncDependencies($toJson = true)
     {
         $dependencies = \call_user_func([$this->getDecoratedObject()->className, 'getSyncDependencies']);
 
-        return ($toJson) ? JSON::encode($dependencies) : $dependencies;
+        return ($toJson) ? \json_encode($dependencies, \JSON_THROW_ON_ERROR) : $dependencies;
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/system/endpoint/controller/core/files/PrepareUpload.class.php b/wcfsetup/install/files/lib/system/endpoint/controller/core/files/PrepareUpload.class.php
index 65091b343fa..1b3b43111b5 100644
--- a/wcfsetup/install/files/lib/system/endpoint/controller/core/files/PrepareUpload.class.php
+++ b/wcfsetup/install/files/lib/system/endpoint/controller/core/files/PrepareUpload.class.php
@@ -11,11 +11,9 @@
 use wcf\system\endpoint\IController;
 use wcf\system\endpoint\PostRequest;
 use wcf\system\exception\PermissionDeniedException;
-use wcf\system\exception\SystemException;
 use wcf\system\exception\UserInputException;
 use wcf\system\file\processor\FileProcessor;
 use wcf\system\file\processor\FileProcessorPreflightResult;
-use wcf\util\JSON;
 use WoltLab\WebpExif\Chunk\Exif;
 
 /**
@@ -39,8 +37,8 @@ public function __invoke(ServerRequestInterface $request, array $variables): Res
         }
 
         try {
-            $decodedContext = JSON::decode($parameters->context);
-        } catch (SystemException) {
+            $decodedContext = \json_decode($parameters->context, true, flags: \JSON_THROW_ON_ERROR);
+        } catch (\JsonException) {
             throw new UserInputException('context', 'invalid');
         }
 
diff --git a/wcfsetup/install/files/lib/system/exception/AJAXException.class.php b/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
index c4eced7d06c..9e265aa4d26 100644
--- a/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
+++ b/wcfsetup/install/files/lib/system/exception/AJAXException.class.php
@@ -5,7 +5,6 @@
 use Throwable;
 use wcf\system\WCF;
 use wcf\system\WCFACP;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -175,7 +174,7 @@ public function __construct(
 
         \header($statusHeader);
         \header('Content-type: application/json; charset=UTF-8');
-        echo JSON::encode($responseData);
+        echo \json_encode($responseData, \JSON_THROW_ON_ERROR);
 
         exit;
     }
diff --git a/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php b/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
index c2171d05736..27671470de4 100644
--- a/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
+++ b/wcfsetup/install/files/lib/system/file/processor/FileProcessor.class.php
@@ -23,7 +23,6 @@
 use wcf\system\WCF;
 use wcf\util\ExifUtil;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 use function wcf\functions\exception\logThrowable;
@@ -129,11 +128,11 @@ public function getHtmlElement(IFileProcessor $fileProcessor, array $context): s
                 ></woltlab-core-file-upload>
                 HTML,
             StringUtil::encodeHTML($fileProcessor->getObjectTypeName()),
-            StringUtil::encodeHTML(JSON::encode($context)),
+            StringUtil::encodeHTML(\json_encode($context, \JSON_THROW_ON_ERROR)),
             StringUtil::encodeHTML($allowedFileExtensions),
-            StringUtil::encodeHTML(JSON::encode($fileProcessor->getResizeConfiguration())),
+            StringUtil::encodeHTML(\json_encode($fileProcessor->getResizeConfiguration(), \JSON_THROW_ON_ERROR)),
             $cropperConfiguration === null ? ''
-                : 'data-cropper-configuration="' . StringUtil::encodeHTML(JSON::encode($cropperConfiguration)) . '"',
+                : 'data-cropper-configuration="' . StringUtil::encodeHTML(\json_encode($cropperConfiguration, \JSON_THROW_ON_ERROR)) . '"',
             $maximumCount,
             $maximumSize,
         );
@@ -375,7 +374,7 @@ public function hasReachedUploadLimit(IFileProcessor $fileProcessor, array $cont
         $statement = WCF::getDB()->prepare($sql);
         $statement->execute([
             $this->getObjectType($fileProcessor->getObjectTypeName())->objectTypeID,
-            JSON::encode($context),
+            \json_encode($context, \JSON_THROW_ON_ERROR),
         ]);
         $numberOfTemporaryFiles = $statement->fetchSingleColumn();
         if ($existingFiles + $numberOfTemporaryFiles >= $maximumCount) {
diff --git a/wcfsetup/install/files/lib/system/form/option/TSelectOptionsFormOption.class.php b/wcfsetup/install/files/lib/system/form/option/TSelectOptionsFormOption.class.php
index 5e0acc9a18b..9f9a478498d 100644
--- a/wcfsetup/install/files/lib/system/form/option/TSelectOptionsFormOption.class.php
+++ b/wcfsetup/install/files/lib/system/form/option/TSelectOptionsFormOption.class.php
@@ -4,7 +4,6 @@
 
 use wcf\system\form\builder\field\ISelectionFormField;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Provides helper methods for form options that use select options.
@@ -26,7 +25,7 @@ protected function setSelectOptions(ISelectionFormField $formField, array $confi
         }
 
         $selectOptions = [];
-        foreach (JSON::decode($configuration['selectOptions']) as $selectOption) {
+        foreach (\json_decode($configuration['selectOptions'], true, flags: \JSON_THROW_ON_ERROR) as $selectOption) {
             if (isset($selectOption['value'][0])) {
                 $value = $selectOption['value'][0];
             } else if (isset($selectOption['value'][WCF::getLanguage()->languageID])) {
diff --git a/wcfsetup/install/files/lib/system/form/option/formatter/MultipleSelectionFormatter.class.php b/wcfsetup/install/files/lib/system/form/option/formatter/MultipleSelectionFormatter.class.php
index 3fe220f36f3..d9b4d91500d 100644
--- a/wcfsetup/install/files/lib/system/form/option/formatter/MultipleSelectionFormatter.class.php
+++ b/wcfsetup/install/files/lib/system/form/option/formatter/MultipleSelectionFormatter.class.php
@@ -2,7 +2,7 @@
 
 namespace wcf\system\form\option\formatter;
 
-use wcf\util\JSON;
+
 use wcf\util\StringUtil;
 
 /**
@@ -23,7 +23,7 @@ public function format(string $value, int $languageID, array $configuration): st
         };
 
         $keys = \explode(",", $value);
-        $selectOptions = JSON::decode($configuration['selectOptions']);
+        $selectOptions = \json_decode($configuration['selectOptions'], true, flags: \JSON_THROW_ON_ERROR);
         $html = '';
 
         foreach ($keys as $key) {
diff --git a/wcfsetup/install/files/lib/system/form/option/formatter/SelectFormatter.class.php b/wcfsetup/install/files/lib/system/form/option/formatter/SelectFormatter.class.php
index 989d72e0028..5145a777b16 100644
--- a/wcfsetup/install/files/lib/system/form/option/formatter/SelectFormatter.class.php
+++ b/wcfsetup/install/files/lib/system/form/option/formatter/SelectFormatter.class.php
@@ -2,7 +2,7 @@
 
 namespace wcf\system\form\option\formatter;
 
-use wcf\util\JSON;
+
 use wcf\util\StringUtil;
 
 /**
@@ -20,7 +20,7 @@ public function __construct(private readonly bool $encode = true) {}
     #[\Override]
     public function format(string $value, int $languageID, array $configuration): string
     {
-        foreach (JSON::decode($configuration['selectOptions']) as $selectOption) {
+        foreach (\json_decode($configuration['selectOptions'], true, flags: \JSON_THROW_ON_ERROR) as $selectOption) {
             if ($selectOption['key'] == $value) {
                 if (isset($selectOption['value'][0])) {
                     $value = $selectOption['value'][0];
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
index 593b0b1be42..7f838740ab2 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeImg.class.php
@@ -8,7 +8,6 @@
 use wcf\system\bbcode\BBCodeParser;
 use wcf\system\html\node\AbstractHtmlNodeProcessor;
 use wcf\util\DOMUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -149,7 +148,7 @@ protected function handleAttachment(\DOMElement $element, $class)
 
         $newElement = $element->ownerDocument->createElement('woltlab-metacode');
         $newElement->setAttribute('data-name', 'attach');
-        $newElement->setAttribute('data-attributes', \base64_encode(JSON::encode($attributes)));
+        $newElement->setAttribute('data-attributes', \base64_encode(\json_encode($attributes, \JSON_THROW_ON_ERROR)));
         DOMUtil::replaceElement($replaceElement, $newElement, false);
     }
 
@@ -207,7 +206,7 @@ private function handleMedium(\DOMElement $element): void
 
         $newElement = $element->ownerDocument->createElement('woltlab-metacode');
         $newElement->setAttribute('data-name', 'wsm');
-        $newElement->setAttribute('data-attributes', \base64_encode(JSON::encode($attributes)));
+        $newElement->setAttribute('data-attributes', \base64_encode(\json_encode($attributes, \JSON_THROW_ON_ERROR)));
         DOMUtil::replaceElement($replaceElement, $newElement, false);
 
         // The media bbcode is a block element that may not be placed inside inline elements.
diff --git a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
index bb82a747c42..631294e1331 100644
--- a/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
+++ b/wcfsetup/install/files/lib/system/html/input/node/HtmlInputNodeTextParser.class.php
@@ -13,7 +13,6 @@
 use wcf\system\database\util\PreparedStatementConditionBuilder;
 use wcf\system\WCF;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -386,7 +385,7 @@ protected function parseMention(\DOMText $text, string $value, array $users, arr
                 if ($pos !== false) {
                     $element = $text->ownerDocument->createElement('woltlab-metacode');
                     $element->setAttribute('data-name', $bbcodeTagName);
-                    $element->setAttribute('data-attributes', \base64_encode(JSON::encode([$objectID])));
+                    $element->setAttribute('data-attributes', \base64_encode(\json_encode([$objectID], \JSON_THROW_ON_ERROR)));
                     $element->appendChild($text->ownerDocument->createTextNode($objectTitle));
 
                     $marker = $this->addReplacement($text, $element);
diff --git a/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php b/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
index 484834d9e92..c3f4dcdc4af 100644
--- a/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
+++ b/wcfsetup/install/files/lib/system/html/node/HtmlNodePlainLink.class.php
@@ -7,7 +7,6 @@
 use wcf\data\ITitledObject;
 use wcf\system\Regex;
 use wcf\util\DOMUtil;
-use wcf\util\JSON;
 
 /**
  * Wrapper for links that do not have a dedicated title and are most likely the result of
@@ -171,7 +170,7 @@ public function replaceWithBBCode(BBCode $bbcode, $overrideObjectID = null)
         $metacodeElement->setAttribute('data-name', $bbcode->bbcodeTag);
         $metacodeElement->setAttribute(
             'data-attributes',
-            \base64_encode(JSON::encode([($overrideObjectID !== null ? $overrideObjectID : $this->objectID)]))
+            \base64_encode(\json_encode([($overrideObjectID !== null ? $overrideObjectID : $this->objectID)], \JSON_THROW_ON_ERROR))
         );
 
         if ($bbcode->isBlockElement) {
diff --git a/wcfsetup/install/files/lib/system/importer/AbstractAttachmentImporter.class.php b/wcfsetup/install/files/lib/system/importer/AbstractAttachmentImporter.class.php
index 7311fb78c2b..cea149ac5ae 100644
--- a/wcfsetup/install/files/lib/system/importer/AbstractAttachmentImporter.class.php
+++ b/wcfsetup/install/files/lib/system/importer/AbstractAttachmentImporter.class.php
@@ -6,7 +6,6 @@
 use wcf\data\attachment\AttachmentEditor;
 use wcf\system\exception\SystemException;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 
 /**
  * Imports attachments.
@@ -127,12 +126,12 @@ static function (array $matches) use ($oldID, $newID): string {
                 $base64Decoded = \base64_decode($matches['attributes']);
                 if ($base64Decoded) {
                     try {
-                        $attributes = JSON::decode($base64Decoded);
+                        $attributes = \json_decode($base64Decoded, true, flags: \JSON_THROW_ON_ERROR);
                         if ($attributes[0] == $oldID) {
                             $attributes[0] = $newID;
                         }
 
-                        $encodedAttributes = \base64_encode(JSON::encode($attributes));
+                        $encodedAttributes = \base64_encode(\json_encode($attributes, \JSON_THROW_ON_ERROR));
                     } catch (\Exception $e) {
                         $encodedAttributes = $matches['attributes'];
                     }
diff --git a/wcfsetup/install/files/lib/system/interaction/bulk/BulkFormBuilderDialogInteraction.class.php b/wcfsetup/install/files/lib/system/interaction/bulk/BulkFormBuilderDialogInteraction.class.php
index caabefafd6c..f65e788610f 100644
--- a/wcfsetup/install/files/lib/system/interaction/bulk/BulkFormBuilderDialogInteraction.class.php
+++ b/wcfsetup/install/files/lib/system/interaction/bulk/BulkFormBuilderDialogInteraction.class.php
@@ -5,7 +5,7 @@
 use wcf\data\DatabaseObject;
 use wcf\system\request\LinkHandler;
 use wcf\system\WCF;
-use wcf\util\JSON;
+
 use wcf\util\StringUtil;
 
 /**
@@ -40,7 +40,7 @@ public function render(array $objects): string
         );
 
         $jsonObjectIDs = StringUtil::encodeHTML(
-            JSON::encode($objectIDs)
+            \json_encode($objectIDs, \JSON_THROW_ON_ERROR)
         );
 
         return <<<HTML
diff --git a/wcfsetup/install/files/lib/system/interaction/bulk/BulkRpcInteraction.class.php b/wcfsetup/install/files/lib/system/interaction/bulk/BulkRpcInteraction.class.php
index c4155a29b83..f71f4a720ba 100644
--- a/wcfsetup/install/files/lib/system/interaction/bulk/BulkRpcInteraction.class.php
+++ b/wcfsetup/install/files/lib/system/interaction/bulk/BulkRpcInteraction.class.php
@@ -7,7 +7,7 @@
 use wcf\system\interaction\InteractionConfirmationType;
 use wcf\system\request\LinkHandler;
 use wcf\system\WCF;
-use wcf\util\JSON;
+
 use wcf\util\StringUtil;
 
 /**
@@ -42,8 +42,9 @@ public function render(array $objects): string
             LinkHandler::getInstance()->getControllerLink(ApiAction::class, ['id' => 'rpc']) . $this->endpoint
         );
         $objectIDs = StringUtil::encodeHTML(
-            JSON::encode(
-                \array_values(\array_map(fn(DatabaseObject $object) => $object->getObjectID(), $objects))
+            \json_encode(
+                \array_values(\array_map(fn(DatabaseObject $object) => $object->getObjectID(), $objects)),
+                \JSON_THROW_ON_ERROR
             )
         );
 
diff --git a/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php b/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
index 9004d25ced1..e014e69c4f5 100644
--- a/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageInstallationDispatcher.class.php
@@ -41,7 +41,6 @@
 use wcf\util\CryptoUtil;
 use wcf\util\FileUtil;
 use wcf\util\HeaderUtil;
-use wcf\util\JSON;
 
 /**
  * PackageInstallationDispatcher handles the whole installation process.
@@ -388,7 +387,7 @@ protected function logInstallationStep(array $node = [], string $log = ''): void
 
             $nodeData = \unserialize($node['nodeData']);
             foreach ($nodeData as $index => $value) {
-                $logEntry .= "\t" . $index . ': ' . (!\is_object($value) && !\is_array($value) ? $value : JSON::encode($value)) . "\n";
+                $logEntry .= "\t" . $index . ': ' . (!\is_object($value) && !\is_array($value) ? $value : \json_encode($value, \JSON_THROW_ON_ERROR)) . "\n";
             }
         }
 
diff --git a/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php b/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
index 249805c6623..d8618bb9a6e 100644
--- a/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
+++ b/wcfsetup/install/files/lib/system/package/PackageUpdateDispatcher.class.php
@@ -19,7 +19,6 @@
 use wcf\system\package\validation\PackageValidationException;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use wcf\util\XML;
 
@@ -151,7 +150,7 @@ private function fetchPurchasedVersions(): void
         try {
             $response = $client->send($request);
 
-            $reply = JSON::decode((string)$response->getBody());
+            $reply = \json_decode((string)$response->getBody(), true, flags: \JSON_THROW_ON_ERROR);
 
             if ($reply['status'] == 200) {
                 $this->hasAuthCode = true;
@@ -160,7 +159,7 @@ private function fetchPurchasedVersions(): void
                     'pluginstore' => ($reply['pluginstore'] ?? []),
                 ];
             }
-        } catch (ClientExceptionInterface | SystemException) {
+        } catch (ClientExceptionInterface | \JsonException) {
             // ignore
         }
     }
diff --git a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
index c2b44892b16..f9c6afe7233 100644
--- a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
@@ -28,7 +28,6 @@
 use wcf\system\user\activity\point\UserActivityPointHandler;
 use wcf\system\user\notification\UserNotificationHandler;
 use wcf\system\WCF;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 
 /**
@@ -89,7 +88,7 @@ public function getReactionsJSVariable()
             ];
         }
 
-        return JSON::encode($returnValues);
+        return \json_encode($returnValues, \JSON_THROW_ON_ERROR);
     }
 
     /**
diff --git a/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php b/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
index 351c87ff16e..404019ca568 100644
--- a/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
+++ b/wcfsetup/install/files/lib/system/style/StyleCompiler.class.php
@@ -16,7 +16,6 @@
 use wcf\command\style\CreateManifest;
 use wcf\system\WCF;
 use wcf\util\FileUtil;
-use wcf\util\JSON;
 use wcf\util\StringUtil;
 use wcf\util\StyleUtil;
 use wcf\util\Url;
@@ -764,7 +763,7 @@ private function writeCss(string $filePrefix, string $css, ?array $preloadManife
         FileUtil::makeWritable($filePrefix . '-rtl.css');
 
         if ($preloadManifest) {
-            \file_put_contents($filePrefix . '-preload.json', JSON::encode($preloadManifest));
+            \file_put_contents($filePrefix . '-preload.json', \json_encode($preloadManifest, \JSON_THROW_ON_ERROR));
             FileUtil::makeWritable($filePrefix . '-preload.json');
         }
     }
diff --git a/wcfsetup/install/files/lib/system/style/StyleHandler.class.php b/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
index 84de647ae5c..9363dc02656 100644
--- a/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
+++ b/wcfsetup/install/files/lib/system/style/StyleHandler.class.php
@@ -10,7 +10,6 @@
 use wcf\system\request\RequestHandler;
 use wcf\system\SingletonFactory;
 use wcf\system\WCF;
-use wcf\util\JSON;
 
 /**
  * Handles styles.
@@ -287,7 +286,7 @@ public function showColorSchemeSelector(): bool
     public function getIcons($toJSON = false)
     {
         if ($toJSON) {
-            return JSON::encode([]);
+            return \json_encode([], \JSON_THROW_ON_ERROR);
         }
 
         return [];
diff --git a/wcfsetup/install/files/lib/system/template/plugin/IconFunctionTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/IconFunctionTemplatePlugin.class.php
index a544e5916cb..a9bb092de24 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/IconFunctionTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/IconFunctionTemplatePlugin.class.php
@@ -7,7 +7,6 @@
 use wcf\system\style\FontAwesomeIconBrand;
 use wcf\system\style\IFontAwesomeIcon;
 use wcf\system\template\TemplateEngine;
-use wcf\util\JSON;
 
 /**
  * Template function plugin that embeds icons into the page. The
@@ -67,7 +66,7 @@ public function execute($tagArgs, TemplateEngine $tplObj)
         $html = $icon->toHtml($size);
 
         if ($encodeJson) {
-            return JSON::encode($html);
+            return \json_encode($html, \JSON_THROW_ON_ERROR);
         }
 
         return $html;
diff --git a/wcfsetup/install/files/lib/system/template/plugin/IconPrefilterTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/IconPrefilterTemplatePlugin.class.php
index 67fceda4a15..6395c4fb0e2 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/IconPrefilterTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/IconPrefilterTemplatePlugin.class.php
@@ -7,7 +7,6 @@
 use wcf\system\style\FontAwesomeIconBrand;
 use wcf\system\style\IFontAwesomeIcon;
 use wcf\system\template\TemplateScriptingCompiler;
-use wcf\util\JSON;
 
 /**
  * See IconFunctionTemplatePlugin.
@@ -41,7 +40,7 @@ function ($match) {
                     $html = $this->getIcon($type, $name)->toHtml($size);
 
                     if ($encodeJson) {
-                        return JSON::encode($html);
+                        return \json_encode($html, \JSON_THROW_ON_ERROR);
                     }
 
                     return $html;
diff --git a/wcfsetup/install/files/lib/system/template/plugin/JsonModifierTemplatePlugin.class.php b/wcfsetup/install/files/lib/system/template/plugin/JsonModifierTemplatePlugin.class.php
index 2194b1d1350..d9053e438a3 100644
--- a/wcfsetup/install/files/lib/system/template/plugin/JsonModifierTemplatePlugin.class.php
+++ b/wcfsetup/install/files/lib/system/template/plugin/JsonModifierTemplatePlugin.class.php
@@ -3,7 +3,6 @@
 namespace wcf\system\template\plugin;
 
 use wcf\system\template\TemplateEngine;
-use wcf\util\JSON;
 
 /**
  * JSON encodes the given value.
@@ -28,6 +27,6 @@ class JsonModifierTemplatePlugin implements IModifierTemplatePlugin
      */
     public function execute($tagArgs, TemplateEngine $tplObj)
     {
-        return JSON::encode($tagArgs[0]);
+        return \json_encode($tagArgs[0], \JSON_THROW_ON_ERROR);
     }
 }
diff --git a/wcfsetup/install/files/lib/util/ExceptionLogUtil.class.php b/wcfsetup/install/files/lib/util/ExceptionLogUtil.class.php
index 0a680eacb19..f5aef43d0bf 100644
--- a/wcfsetup/install/files/lib/util/ExceptionLogUtil.class.php
+++ b/wcfsetup/install/files/lib/util/ExceptionLogUtil.class.php
@@ -98,7 +98,7 @@ public static function parseException($entry)
             }
 
             try {
-                $item['stack'] = JSON::decode($item['stack']);
+                $item['stack'] = \json_decode($item['stack'], true, flags: \JSON_THROW_ON_ERROR);
             } catch (SystemException $e) {
                 throw new \InvalidArgumentException('The stack trace of the given entry is malformed.', 0, $e);
             }
diff --git a/wcfsetup/install/files/lib/util/UserUtil.class.php b/wcfsetup/install/files/lib/util/UserUtil.class.php
index 6fc505dd72e..f6ad7894a67 100644
--- a/wcfsetup/install/files/lib/util/UserUtil.class.php
+++ b/wcfsetup/install/files/lib/util/UserUtil.class.php
@@ -3,7 +3,6 @@
 namespace wcf\util;
 
 use wcf\system\email\Mailbox;
-use wcf\system\exception\SystemException;
 use wcf\system\WCF;
 
 /**
@@ -252,11 +251,12 @@ public static function getRequestURI(): string
      */
     public static function createGuestToken(string $username): string
     {
-        return CryptoUtil::createSignedString(JSON::encode(
+        return CryptoUtil::createSignedString(\json_encode(
             [
                 'username' => $username,
                 'time' => TIME_NOW,
-            ]
+            ],
+            \JSON_THROW_ON_ERROR
         ));
     }
 
@@ -278,8 +278,8 @@ public static function verifyGuestToken(string $token): ?string
         }
 
         try {
-            $data = JSON::decode($json);
-        } catch (SystemException $e) {
+            $data = \json_decode($json, true, flags: \JSON_THROW_ON_ERROR);
+        } catch (\JsonException) {
             return null;
         }