diff -u b/core/modules/system/src/Form/ModulesListForm.php b/core/modules/system/src/Form/ModulesListForm.php
--- b/core/modules/system/src/Form/ModulesListForm.php
+++ b/core/modules/system/src/Form/ModulesListForm.php
@@ -147,7 +147,7 @@
       uasort($modules, 'system_sort_modules_by_info_name');
     }
     catch (InfoParserException $e) {
-      $this->messenger()->addError($this->t('Modules could not be listed due to an error: "%error"', ['%error' => $e->getMessage()]));
+      $this->messenger()->addError($this->t('Modules can not be listed due to an error: %error', [%error => $e->getMessage()]));
       $modules = [];
     }
 
diff -u b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
--- b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ModulesListFormWebTest.php
@@ -70,7 +70,7 @@
 
     // Confirm that the error message is shown.
     $this->assertSession()
-      ->pageTextContains('Modules could not be listed due to an error: "Missing required keys (core) in ' . $path . '/broken.info.yml"');
+      ->pageTextContains('Modules can not be listed due to an error: "Missing required keys (core) in ' . $path . '/broken.info.yml"');
 
     // Check that the module filter text box is available.
     $this->assertTrue($this->xpath('//input[@name="text"]'));