Doctrine Error While Logging In

Whenever I am Trying to login, i get an error page and when I check log it shows following error -

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing ‘SELECT id, numeric_id, available, last_checked FROM oc_storages WHERE id IN (?)’ with params [“local::/home/admin/web/”]: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away

Nextcloud version : 14.0.3
Operating system and version : Ubuntu 18.04
Apache or version : 2.4.37
PHP version : 7.2

Is this the first time you’ve seen this error? : Y

We are using the best system and it occur some error which is really harmful to the system. And I also use the printer in the system and if I have any issue with printer then go to the canon copier repair which provide the good service. which is good for us.