Not connecting to nextcloud after debian update


I’m sorry about the lack of details, I’m still a bit of a beginner, so don’t hesitate to tell me what could be required to help me solve my issue.
I recently updated both my nextcloud platform and my debian server (apt update & upgrade, nothing much), and realized today that the nextcloud is not working anymore, telling me there is an “internal server error”.
The nextcloud worked after its update, but not after the debian update, but I can’t remember which updates were performed (do you have any way to find this out?).
If this helps, I also noticed that the nextcloud’s calendar is unavailable from my thunderbird app’.

I copied the related logs on this pastebin, but I’m unable to understand any of this… : {"reqId":"0aJr91O5nTBDPc6w4jha","level":3,"time":"2021-02-09T20:49:59+00:00","re -

Do you have any idea of what could possibly have gone wrong, and how to correct it?

Thanks a lot!