HTTP error 500 after failed update to 20.0.2

Nextcloud version (eg, 18.0.2): 20.0.2
Operating system and version (eg, Ubuntu 20.04): unraid 6.8.3
Apache or nginx version (eg, Apache 2.4.25): ??
PHP version (eg, 7.1):???

The issue you are facing:

Firstly, I am a noob so this may be very trivial…I updated to the latest version today, all was fine until I hit the ‘no to maintenance mode’. As soon as I did I was presented with the ‘this page isn’t working, http error 500’ screen. I now can’t get to my web gui and always get that screen.

In the unraid log i get the following repeated message:

PHP Fatal error: Interface ‘OCA\Files_External\Lib\Config\IBackendProvider’ not found in /config/www/nextcloud/apps/files_external_gdrive/lib/AppInfo/Application.php on line 32

Can anyone shed some light on this and advise on a fix please. Thanks in advance.