diff --git a/src/commands/build/upload.rs b/src/commands/build/upload.rs
index c47e948df2..bf24d84b8f 100644
--- a/src/commands/build/upload.rs
+++ b/src/commands/build/upload.rs
@@ -325,7 +325,15 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
             }
         );
         for (path, reason) in errored_paths_and_reasons {
-            warn!("  - {} ({})", path.display(), reason);
+            let reason_str = reason.to_string();
+            // Provide specific guidance for project not found errors
+            if reason_str.contains("Project not found") {
+                warn!("  - {}", path.display());
+                warn!("    Project not found. Ensure that you configured the correct project and organization.");
+                warn!("    Use --project and --org flags to specify the correct values.");
+            } else {
+                warn!("  - {} ({})", path.display(), reason);
+            }
         }
     }
 
diff --git a/tests/integration/_cases/build/build-upload-nonexistent-project.trycmd b/tests/integration/_cases/build/build-upload-nonexistent-project.trycmd
new file mode 100644
index 0000000000..5d38a38c04
--- /dev/null
+++ b/tests/integration/_cases/build/build-upload-nonexistent-project.trycmd
@@ -0,0 +1,15 @@
+```
+$ sentry-cli build upload tests/integration/_fixtures/build/apk.apk --project nonexistentproject
+? failed
+[..]WARN[..]EXPERIMENTAL: The build subcommand is experimental. The command is subject to breaking changes and may be removed without notice in any release.
+  WARN    [..] Could not detect base branch reference: [..]
+  WARN    [..] Failed to upload 1 file:
+  WARN    [..]   - [..]apk.apk
+  WARN    [..]     Project not found. Ensure that you configured the correct project and organization.
+  WARN    [..]     Use --project and --org flags to specify the correct values.
+error: Failed to upload any files
+
+Add --log-level=[info|debug] or export SENTRY_LOG_LEVEL=[info|debug] to see more output.
+Please attach the full debug log to all bug reports.
+
+```
\ No newline at end of file
diff --git a/tests/integration/build/upload.rs b/tests/integration/build/upload.rs
index 93d5ca9ddd..b1cae95549 100644
--- a/tests/integration/build/upload.rs
+++ b/tests/integration/build/upload.rs
@@ -74,6 +74,25 @@ fn command_build_upload_invalid_ipa() {
         .run_and_assert(AssertCommand::Failure);
 }
 
+#[test]
+fn command_build_upload_nonexistent_project() {
+    TestManager::new()
+        .mock_endpoint(
+            MockEndpointBuilder::new("GET", "/api/0/organizations/wat-org/chunk-upload/")
+                .with_response_file("build/get-chunk-upload.json"),
+        )
+        .mock_endpoint(
+            MockEndpointBuilder::new(
+                "POST",
+                "/api/0/projects/wat-org/nonexistentproject/files/preprodartifacts/assemble/",
+            )
+            .with_status(404)
+            .with_response_body(r#"{"detail":"Project not found. Ensure that you configured the correct project and organization."}"#),
+        )
+        .register_trycmd_test("build/build-upload-nonexistent-project.trycmd")
+        .with_default_token();
+}
+
 #[test]
 fn command_build_upload_apk_all_uploaded() {
     TestManager::new()