diff --git a/sormas-api/src/main/java/de/symeda/sormas/api/i18n/Strings.java b/sormas-api/src/main/java/de/symeda/sormas/api/i18n/Strings.java
index ebc166eab95..950cfc14c65 100644
--- a/sormas-api/src/main/java/de/symeda/sormas/api/i18n/Strings.java
+++ b/sormas-api/src/main/java/de/symeda/sormas/api/i18n/Strings.java
@@ -1173,6 +1173,7 @@ public interface Strings {
 	String infoSyncUsers = "infoSyncUsers";
 	String infoSystemConfigurationValueDescriptionEmailSenderAddress = "infoSystemConfigurationValueDescriptionEmailSenderAddress";
 	String infoSystemConfigurationValueDescriptionEmailSenderName = "infoSystemConfigurationValueDescriptionEmailSenderName";
+	String infoSystemConfigurationValueDescriptionMenuBackgroundColor = "infoSystemConfigurationValueDescriptionMenuBackgroundColor";
 	String infoSystemConfigurationValueDescriptionSmsAuthKey = "infoSystemConfigurationValueDescriptionSmsAuthKey";
 	String infoSystemConfigurationValueDescriptionSmsAuthSecret = "infoSystemConfigurationValueDescriptionSmsAuthSecret";
 	String infoSystemConfigurationValueDescriptionSmsSenderName = "infoSystemConfigurationValueDescriptionSmsSenderName";
diff --git a/sormas-api/src/main/resources/strings.properties b/sormas-api/src/main/resources/strings.properties
index 3d394e17124..d490292afa0 100644
--- a/sormas-api/src/main/resources/strings.properties
+++ b/sormas-api/src/main/resources/strings.properties
@@ -2018,6 +2018,7 @@ infoSystemConfigurationValueDescriptionSmsSenderName=Name that will be set as th
 infoSystemConfigurationValueDescriptionSmsAuthKey=SORMAS supports the delivery of SMS notifications via Vonage (https://www.vonage.com/communications-apis/). You need to specify a valid authentication key and secret in order to use this feature. SORMAS will not attempt to send out SMS if these properties are left empty.
 infoSystemConfigurationValueDescriptionSmsAuthSecret=Secret for SMS authentication.
 infoSystemConfigurationValueDescriptionUseDeterminedVaccinationStatus=Use automatic vaccination status. The status will be derived from vaccination data.
+infoSystemConfigurationValueDescriptionMenuBackgroundColor=Allows to change background color of the menu to distinguish between different SORMAS instances.
 
 notificationCannotCreate=Cannot Create Or Edit Notification
 notificationCreationNotAllowedWithoutSurveillanceReport=Notifier creation or modification is not allowed when a surveillance report already exists for this case.
diff --git a/sormas-api/src/main/resources/validations.properties b/sormas-api/src/main/resources/validations.properties
index e4b5a628975..00c7618f90e 100644
--- a/sormas-api/src/main/resources/validations.properties
+++ b/sormas-api/src/main/resources/validations.properties
@@ -330,5 +330,5 @@ systemConfigurationValueValidationNotAValidEmailsenderName = Value is not a vali
 systemConfigurationValueValidationNotAValidSmsSenderName = Value is not a valid name. Name should contain only letters and numbers without spaces & special characters. For more info please see https://developer.vonage.com/en/messaging/sms/guides/custom-sender-id .
 smsAuthKeyValueValidation = SMS Auth key value is not valid
 smsAuthSecretValueValidation = SMS Auth secret value is not valid
-systemConfigurationValueValidationInvalidBackgroundColor = Pre-defined values are: green, red, indigo, gray, default (case-sensitive) otherwise must match hexadecimal format, example: #dd2b0e or #4AA
+systemConfigurationValueValidationInvalidBackgroundColor = Pre-defined values are: green, red, indigo, gray, default (case-sensitive) otherwise must match hexadecimal format (with or without hash "#"), example: #dd2b0e or #4AA or dd2b0e
 systemConfigurationValueValidationMenuSubtitle = Can be empty or up to 16 (any) characters. Can be used to define name of the environment: PRODUCTION - TEST etc.
diff --git a/sormas-backend/src/main/resources/sql/sormas_schema.sql b/sormas-backend/src/main/resources/sql/sormas_schema.sql
index 312be0de5ef..145e21dbba8 100644
--- a/sormas-backend/src/main/resources/sql/sormas_schema.sql
+++ b/sormas-backend/src/main/resources/sql/sormas_schema.sql
@@ -15770,4 +15770,17 @@ UPDATE diseaseconfiguration SET exposurecategories = 'VECTOR_BORNE' WHERE diseas
 
 INSERT INTO schema_version (version_number, comment) VALUES (622, '#13887 default disease exposure category configuration');
 
--- *** Insert new sql commands BEFORE this line. Remember to always consider _history tables. ***
+-- updated regexes for MENU system config values
+UPDATE systemconfigurationvalue
+SET value_pattern = '^(default|red|green|indigo|gray)$|^(#?([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3}))$',
+value_description = 'i18n/infoSystemConfigurationValueDescriptionMenuBackgroundColor',
+validation_message = 'i18n/systemConfigurationValueValidationInvalidBackgroundColor'
+WHERE config_key = 'MENU_BACKGROUND_COLOR';
+
+UPDATE systemconfigurationvalue
+SET value_pattern = '^[\w\s]{0,16}$'
+WHERE config_key = 'MENU_SUBTITLE';
+
+INSERT INTO schema_version (version_number, comment) VALUES (623, '#13552 - FIX menu regexes');
+
+-- *** Insert new sql commands BEFORE this line. Remember to always consider _history tables. ***
\ No newline at end of file
diff --git a/sormas-ui/src/main/java/de/symeda/sormas/ui/Menu.java b/sormas-ui/src/main/java/de/symeda/sormas/ui/Menu.java
index 0dad140391f..177b24d8b11 100644
--- a/sormas-ui/src/main/java/de/symeda/sormas/ui/Menu.java
+++ b/sormas-ui/src/main/java/de/symeda/sormas/ui/Menu.java
@@ -75,6 +75,8 @@ public class Menu extends CssLayout {
 	private static final String COLOR_BACKGROUND_STYLE_NAME = "color-background";
 	private static final String MENU_SUBTITLE_STYLE_NAME = "menu-subtitle";
 	private static final String TOP_MENU_CONTAINER_STYLE_NAME = "top-menu-container";
+	private static final String HASH = "#";
+
 
 	private final Navigator navigator;
 	private final Map<String, Button> viewButtons = new HashMap<>();
@@ -214,11 +216,18 @@ private static void defineMenuSubtitleIfSystemConfigured(VerticalLayout topConta
 			actualColorBackgroundColor = "#737278";
 			break;
 		default:
-			actualColorBackgroundColor = backgroundColor;
+			actualColorBackgroundColor = addHashIfMissing(backgroundColor);
 		}
 		return actualColorBackgroundColor;
 	}
 
+	private static String addHashIfMissing(String backgroundColor) {
+		if (!StringUtils.startsWith(backgroundColor, HASH)) {
+			return HASH + backgroundColor;
+		}
+		return backgroundColor;
+	}
+
 	private void showSettingsPopup() {
 
 		Window window = VaadinUiUtil.createPopupWindow();