Can't url import Office365 ics calendar

[FelixBuehler]

Steps to reproduce

1. Have an office365 calendar shared
2. Add the url as a new calendar (in german: New subscription from link)
3. See that the calendar won't show entries

(4) If you import the previously downloaded ics file, everything works fine.

Expected behavior

The calendar to show entries

Actual behavior

No entries will be shown

Calendar app version

5.3.9

CalDAV-clients used

Thunderbird, DAVx5

Browser

No response

Client operating system

No response

Server operating system

No response

Web server

None

Database engine version

None

PHP engine version

None

Nextcloud version

31.0.8

Updated from an older installed version or fresh install

None

List of activated apps

Nextcloud configuration

Web server error log

Log file

Browser log

Additional info

No response

[FelixBuehler]

Might be the same issue as this?
bitfireAT/icsx5#654 (comment)

[bmajik]

Same issue.

NC looks like it uses this UA and headers for the outgoing request:

                    "headers": {
                        "User-Agent": "Nextcloud Webcal Service",
                        "Accept": "text/calendar, application/calendar+json, application/calendar+xml",
                        "Accept-Encoding": "gzip"
                    }

For some tenants, Microsoft is now rejecting this UA.

[tcitworld]

We could do the same as ICSx⁵, have a custom user-agent if the URL to fetch matches outlook.office365.com.

This is handled here if anyone wants to have a go at it:
https://github.com/nextcloud/server/blob/93b97f49e5b6fce6e03cf9dad3193c5287b1149a/apps/dav/lib/CalDAV/WebcalCaching/Connection.php#L44

[tcitworld]

Yup, that's the idea! Feel free to point your PR at https://github.com/nextcloud/server/ !

[bmajik]

Great, thank you!

nextcloud/server#54564

[bmajik]

Additional investigation comments in bitfireAT/icsx5#655 (comment)