diff --git a/packages/server/modules/shared/authz.ts b/packages/server/modules/shared/authz.ts
index 2aa8152a9..74b90c27b 100644
--- a/packages/server/modules/shared/authz.ts
+++ b/packages/server/modules/shared/authz.ts
@@ -247,7 +247,12 @@ export const validateRequiredStreamFactory =
       if (!stream)
         return authFailed(
           context,
-          new NotFoundError('Stream inputs are malformed'),
+          new NotFoundError(
+            'Project ID is malformed and cannot be found, or the project does not exist',
+            {
+              info: { projectId: params.streamId }
+            }
+          ),
           true
         )
       context.stream = stream
diff --git a/packages/server/modules/shared/test/authz.spec.js b/packages/server/modules/shared/test/authz.spec.js
index 5eb88c971..004c30d96 100644
--- a/packages/server/modules/shared/test/authz.spec.js
+++ b/packages/server/modules/shared/test/authz.spec.js
@@ -380,7 +380,13 @@ describe('AuthZ @shared', () => {
         context: {}
       })
 
-      expectAuthError(new NotFoundError('Stream inputs are malformed'), authResult)
+      expectAuthError(
+        new NotFoundError(
+          'Project ID is malformed and cannot be found, or the project does not exist',
+          { info: { projectId: 'the need for stream' } }
+        ),
+        authResult
+      )
     })
   })
   describe('Escape hatches', () => {