diff --git a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
index 460efa725c..0ae61838a6 100644
--- a/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
@@ -87,7 +87,7 @@ public function testModulesListFormWithInvalidInfoFile() {
 core: 9.x
 core_version_requirement: ^8 || ^9
 BROKEN,
-        'expected_error' => "'core: 9.x' is not supported. Use 'core_version_requirement' to specify core compatibility in $file_path",
+        'expected_error' => "'core: 9.x' is not supported. Use 'core_version_requirement' to specify core compatibility. Only 'core: 8.x' is supported to provide backwards compatibility for Drupal 8 when needed in $file_path",
       ],
     ];