Laravel mysql access denied while package:discover command

I have cloned a new project. and just ran the composer install command. All packages are installed perfectly But I got an error while "post-autoload-dump". The error says

    In Database.php line 154:

  Database error: SQLSTATE[HY000] [1045] Access denied for user ''@'localhost  
  ' (using password: NO) 

I changed credentials for the database in .env file and ran the composer install again. But got the same error again. When I tried to run php artisan config:clear It also returned the above error.

via Chebli Mohamed