This error occurs when Laravel is unable to establish a database connection.
To resolve this issue, check your database configuration in the .env file and ensure that the database credentials are correct. Also, make sure that the database server is running.
If the issue persists, try clearing the configuration cache by running the following command:
php artisan config:clear
If that doesn't work, try clearing the application cache by running:
php artisan cache:clear
If none of these solutions work, try restarting your web server and database server.
If the issue still persists, it may be helpful to provide more information about your Laravel and database setup, as well as any relevant error messages.