I have tried to add my work calendar to kcontact. I have tried to access the url of my calendar with a browser (not logged in into office365) and can download the whole calendar file. I have tried the following two methods to add it to kcontact (Ubuntu 21.10, KContact 5.18.1, now even tested on 22.04 and 5.19.3)

1. "iCal File"
I have insert the url of my calendar as the file and added description. An entry is added to the list of calendars, but with a generic name "akonadi_...". No error message, but no calendar data either. If you open propertied I see that 0bytes were downloaded.

2. "DAV Groupware resource"
It starts with the fact that it requires me to enter credentials (non are needed). Then I chose "manual configuration", delete the credentials and try to add the url. All I get is a HTTP error 400. Then I try with credentials, but I get warned that office365 doesn't require credentials and after I confirm I am back to HTTP error 400.

I tried the same url in thunderbird and evolution and both work without problems.

What am I missing?

Kind regards from Stockholm!

Don't know if this is still relevant - https://userbase.kde.org/Tutorials/Kontact/Office365