Fixes #3968: Messages logged in shutdown functions are not handled

framework/CHANGELOG.md

@@ -50,6 +50,7 @@ Yii Framework 2 Change Log
 - Bug #3863: Fixed incorrect js selector for `\yii\widgets\ActiveForm::errorSummaryCssClass` when it contains multiple classes (creocoder, umneeq)
 - Bug #3909: `Html::to()` should not prefix base URL to URLs that already contain scheme (qiangxue)
 - Bug #3934: yii.handleAction() in yii.js does not correctly detect if a hyperlink contains useful URL or not (joni-jones, qiangxue)
+- Bug #3968: Messages logged in shutdown functions are not handled (qiangxue)
 - Bug: Fixed inconsistent return of `\yii\console\Application::runAction()` (samdark)
 - Bug: URL encoding for the route parameter added to `\yii\web\UrlManager` (klimov-paul)
 - Bug: Fixed the bug that requesting protected or private action methods would cause 500 error instead of 404 (qiangxue)

framework/log/Logger.php

@@ -116,7 +116,10 @@ class Logger extends Component
     public function init()
     {
         parent::init();
-        register_shutdown_function([$this, 'flush'], true);
+        register_shutdown_function(function () {
+            // make sure "flush()" is called last when there are multiple shutdown functions
+            register_shutdown_function([$this, 'flush'], true);
+        });
     }
 
     /**