Fixes #3088: The debug and gii modules will manage their own URL rules now

config/web.php

@@ -41,6 +41,8 @@ if (YII_ENV_DEV) {
     // configuration adjustments for 'dev' environment
     $config['bootstrap'][] = 'debug';
     $config['modules']['debug'] = 'yii\debug\Module';
+
+    $config['bootstrap'][] = 'gii';
     $config['modules']['gii'] = 'yii\gii\Module';
 }