Cannot connect document + error in container log

I installed collabora following the instructions with the docker image and the apache reverse proxy.
If I want to open a document, it loads the frame of collabora (the menu and so on) and it trys to connect but then there is an error saying the document couldn’t be connected to…
Log of the container shows:

(these 4 lines repeating…)

Could anyone help me with this?

im running debian 8 with apache, mysql and with nexcloud 11.0.2

Got the exact same issue

Debian 8, Apache2 reverse proxy NC 11.0.2.

followed the guide every single step.

Nothing on this issue?

nope, sorry…
switched to onlyoffice
was easier to connect with nextcloud and has better implementation of MS Office files