Error: HTTP 400 / Calendar suddenly stopped working

[anijatsu]

Hi,
I'm attaching two files from the davx5-debug zip that has been generated by the application. I've had to redact some confidential information.
Since today, I've stopped being able to sync my mailbox.org (supported as listed on Tested With) Calendars.
The only obvious errors I can see in the logs is the error code 400 from the calendar server's API side (if I understand it correctly). I don't know how to interpret that for this application.

I think this could be related to #328. Should I open this as an issue?

logcat.txt
debug-info.txt

[exstntlmsnthrp]

I've used mailbox.org with DavX⁵ for many years and generally it works well.

Once in awhile, I will see a bad request error like that (400 server error) and occasionally I've seen 500, 503, and 504 errors as well. Thus far, the errors have always resolved relatively quickly. The few times it was slow to resolve were because of emergency server repair/maintenance or when mailbox.org suffered DDoS.

I had seen one this morning as well, both caldav and carddav failed to sync overnight. I ignored it and everything has been syncing fine today.

Edit: I'm not a developer, so I'm not certain. I do know that once I enabled permissions to allow DavX⁵ to have background location, I have seen fewer errors popping up. I see in your debug info that's disabled. It's also interesting that both your carddav and tasks synced without problems, only your calendar.

[anijatsu]

I'll continue monitoring this issue, since the last error is from an hour ago.
I think it could've triggered after I edited a calendar event using aCalendar, but I haven't used any experimental or extended attributes there - just changed the time of one of the instances of a weekly repeating event.

[exstntlmsnthrp]

I think it could've triggered after I edited a calendar event using aCalendar

Yes, I saw that in the logs. I forgot to ask about this.

Not that long ago, I believe someone else reported an error using aCalendar here on GitHub. Not sure if searching discussions would find it or not.