ONLYOFFICE doesn't open Excel- or Word-Files anymore - just download - why?

We are a kindergarten and not IT professionals, so please bear with us.
We use ONLYOFFICE since the beginning about 2 years ago to edit Excel files together.
Since yesterday this no longer works, the files can only be downloaded.
Can anyone tell me why? And maybe how it works after all?

  1. Check in with whoever is managing the system in case something was changed by them yesterday or the day before.

  2. Perhaps your Nextcloud was updated and/or this particular plugin was disabled. They’ll want to login as an admin and check the apps on the top right menu to see if it is currently enabled.

  3. If you still need help I can link you to our support template, but we’ll need to get technical. Here it is:

Hi @tylezone,
You are missing the required support template. Please fill this form out and edit into your post.

This will give us the technical info and logs needed to help you! Thanks.