Occ error: "An unhandled exception has been thrown"

I have been trying to set up Collabora Online in my home installation of Nextcloud. I’m afraid this is beyond my technical abilities. But this is not my problem.
Maybe (or maybe not) related to this, I’m now not able to connect to my server. The Apache server is up and running (it can be seen at https://polkillas.ddns.net) but Nextcloud sends only an empty page and neither desktop nor Android client can sync.
I’ve tried to enable maintenance mode but occ --maintenance:mode --on throws these errors:
> An unhandled exception has been thrown:
> Doctrine\DBAL\DBALException: Failed to connect to the database: An exception occured in driver: SQLSTATE[HY000] [2002] No such file or directory in /var/www/html/nube/lib/private/DB/Connection.php:59
> Stack trace:
> #0 /var/www/html/nube/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(429): OC\DB\Connection->connect()
> #1 /var/www/html/nube/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(389): Doctrine\DBAL\Connection->getDatabasePlatformVersion()
> #2 /var/www/html/nube/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(328): Doctrine\DBAL\Connection->detectDatabasePlatform() >#3 /var/www/html/nube/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Connection.php(621): Doctrine\DBAL\Connection->getDatabasePlatform()
> #4 /var/www/html/nube/lib/private/DB/Connection.php(142): Doctrine\DBAL\Connection->setTransactionIsolation(2) >#5 /var/www/html/nube/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/DriverManager.php(172): OC\DB\Connection->__construct(Array, Object(Doctrine\DBAL\Driver\PDOMySql\Driver), Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager))
> #6 /var/www/html/nube/lib/private/DB/ConnectionFactory.php(121): Doctrine\DBAL\DriverManager::getConnection(Array, Object(Doctrine\DBAL\Configuration), Object(Doctrine\Common\EventManager)) >#7 /var/www/html/nube/lib/private/Server.php(415): OC\DB\ConnectionFactory->getConnection(‘mysql’, Array)
> #8 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC\{closure}(Object(OC\Server)) >#9 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet(‘DatabaseConnect…’)
> #10 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query('DatabaseConnect...') >#11 /var/www/html/nube/lib/private/Server.php(1029): OC\ServerContainer->query(‘DatabaseConnect…’)
> #12 /var/www/html/nube/lib/private/Server.php(220): OC\Server->getDatabaseConnection() >#13 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
> #14 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet('OC\\Authenticati...') >#15 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query(‘OC\Authenticati…’)
> #16 /var/www/html/nube/lib/private/Server.php(224): OC\ServerContainer->query('OC\\Authenticati...') >#17 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
> #18 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet('OC\\Authenticati...') >#19 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query(‘OC\Authenticati…’)
> #20 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(151): OC\ServerContainer->query('OC\\Authenticati...') >#21 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(109): OC\AppFramework\Utility\SimpleContainer->OC\AppFramework\Utility{closure}(Object(OC\Server))
> #22 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet('OC\\Authenticati...') >#23 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query(‘OC\Authenticati…’)
> #24 /var/www/html/nube/lib/private/Server.php(239): OC\ServerContainer->query('OC\\Authenticati...') >#25 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC{closure}(Object(OC\Server))
> #26 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet('UserSession') >#27 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query(‘UserSession’)
> #28 /var/www/html/nube/lib/private/Server.php(906): OC\ServerContainer->query('UserSession') >#29 /var/www/html/nube/lib/private/Server.php(459): OC\Server->getUserSession()
> #30 /var/www/html/nube/3rdparty/pimple/pimple/src/Pimple/Container.php(113): OC\Server->OC\{closure}(Object(OC\Server)) >#31 /var/www/html/nube/lib/private/AppFramework/Utility/SimpleContainer.php(103): Pimple\Container->offsetGet(‘AppManager’)>#32 /var/www/html/nube/lib/private/ServerContainer.php(89): OC\AppFramework\Utility\SimpleContainer->query(‘AppManager’)>#33 /var/www/html/nube/lib/private/Server.php(1206): OC\ServerContainer->query(‘AppManager’)>#34 /var/www/html/nube/lib/private/legacy/app.php(293): OC\Server->getAppManager()>#35 /var/www/html/nube/lib/private/legacy/app.php(109): OC_App::getEnabledApps()>#36 /var/www/html/nube/lib/base.php(658): OC_App::loadApps(Array)>#37 /var/www/html/nube/lib/base.php(1059): OC::init()>#38 /var/www/html/nube/console.php(48): require_once(’/var/www/html/n…’)>#39 /var/www/html/nube/occ(11): require_once(’/var/www/html/n…’)>#40 {main}`

I have absolutly no clue about what may have happened. I do have a backup, but I’d rather not having to resort to it. Thanks!

You need a mysql driver for php-cli too, thats a different one than the one using with apache/nginx.
You need to check with your linux distribution which package is the correct one, you need to install.

I’ll see if I can install it, I’m on Raspbian unstable. Thanks.

Unless you compile collabora from scratch, it won’t work on a raspberry. The Dockerimage contains x64 binaries.