Update stuck, no NextCloud access

I installed my Nextcloud instance on a hosted virtual server along with my website back in 2020. Everything worked fine until I tried updating my version install. Plesk shows an available Update to

The update process appears to be stuck and gives me this message:
"Execution filemng has failed with exit code 255, stdout: #!/usr/bin/env php Nextcloud Updater - version: v19.0.3-8-gbfdc40b Step 5 is currently in process. Please call this command later. , stderr: "
The server log nets me the following 3 consecutive errors when I try and access the Nextcloud site:
Error 500 GET /nextcloud/ HTTP/1.1
Error 500 GET /nextcloud/index.php/js/core/merged-template-prepend.js?v=c115b3a3-30 HTTP/1.1
Error 500 GET /nextcloud/index.php/apps/theming/styles?v=30 HTTP/1.1

I have exhausted my limited know-how on how to analyze or even fix this.
I have regular backups of the database. Would it be o.k. to image the DB, kill the Nextcloud instance, re-install and move the image back?
Any help is appreciated. Thanks!
Cheers, Volker

Try this:
Delete (or move) your $datadirectory/updater-$instanceid/.step* file(s) and start update again.

Much luck,