getting error Fatal error: in vendor/laravel/framework/src/Illuminate/Foundation/Application.php on line 25

I am using laravel 5.5, My project was working fine. Suddenly it start showing below error.

Fatal error: in /home/user/sandbox/project/vendor/laravel/framework/src/Illuminate/Foundation/Application.php on line 25

Here is image of log.

I have tired below solution. But nothing worked

php composer.phar dump-autoload
php composer.phar install --no-scripts
php composer.phar update

Tired removing vendor folder and again running above command.

But to no avial. Please help.

via Chebli Mohamed