Internal Server Error after Ubuntu update

I wanted to update my Ubuntu server and Nextcloud this morning and unfortunately get the following error message after running the update command “sudo apt update && sudo apt upgrade -y”:

Internal Server Error

The server encountered an internal error and was unable to complete your request.
Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.
More details can be found in the server log.

I am stuck here and need help please.

Ubuntu 18.04.5 LTS
Nextcloud 20.0.4.0
Apache/2.4.46
PHP 7.3 fpm
MariaDB 10.3.29

I hope it’s okay that I provide all logfiles and configurations with Google Drive. I really don’t know where to start at the moment. If I post everything here, it will be a mess.

https://drive.google.com/drive/folders/1B9_k7uzsMI8nsmvj6LDnx_28VGgbSSdo?usp=sharing

I would be so grateful if anyone here could help me out.

There are many entries regarding redis. Perhaps try to uncomment the redis stuff from the logs and try again. If it is just this, then verify your redis configuration (is it running, did the config change during the upgrade, are all php-redis modules installed and activated).