Can't update Nextcloud -> parsing response failed

Nextcloud version (20.0.1):
Operating system and version (Raspbian Buster):
Apache or nginx version (Apache 2.4.38):
PHP version (7.3.19):

The issue you are facing:
Hello, after opening the Web Updater, i get an error after the first step. Nothing is written in logs.
I tried restarting but it didnt help


The output of your Apache2:

sh: 1: flatpak: not found
sh: 1: kitinerary-extractor: not found

no errors in nginx reverse proxy log files.

What can i do?
Thank you!