ParseException: Invalid Mimedir file when subscribing to iCloud calendar

Steps to reproduce

Hello,

I’m experiencing an issue when trying to import an iCloud calendar into Nextcloud (AIO). When I add the calendar link as a new “subscription link” to Nextcloud’s calendar, I get the following error in the log:

ParseException Invalid Mimedir file. Line starting at 5971 did not follow iCalendar/vCard conventions. Subscription 30 could not be parsed.

Go to Nextcloud Calendar and add a subscription using the iCloud calendar link (webcal://...).
• The system attempts to parse the iCalendar file.
• An error occurs: ParseException: Invalid Mimedir file. Line starting at 5971 did not follow iCalendar/vCard conventions.

Expected behavior

The iCloud calendar should be successfully imported into the Nextcloud calendar without any parsing errors.

Actual behavior

The calendar subscription fails with the error mentioned above, and the calendar is not imported.

Calendar app version

5.3.4

CalDAV-clients used

macOS Calendar

Browser

Brave

Client operating system

MacOSX

Server operating system

Alpine Linux v3.21

Web server

Nginx

Database engine version

MariaDB

PHP engine version

PHP 8.4

Nextcloud version

31.0.6.2

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

Here's example of one of the events to reproduce:

BEGIN:VEVENT
DTEND;TZID=Europe/Prague:20171201T140000
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS="Prague, Czech Republic";
X-APPLE-MAPKIT-HANDLE=CAES0gEaEgkj0MQhOwpJQBFJTD3+KOcsQCJ1Cg5DemVjaCBSZX
B1YmxpYxICQ1oaBlByYWd1ZSoGUHJhZ3VlMgZQcmFndWU6BjEzMCAwMEIHUHJhaGEgM1INT2
5kxZnDrcSNa292YVoCMjJiEE9uZMWZw63EjWtvdmEgMjKKAQZaaXprb3aKAQdQcmFoYSAzKh
BPbmTFmcOtxI1rb3ZhIDIyMhBPbmTFmcOtxI1rb3ZhIDIyMg0xMzAgMDAgUHJhZ3VlMg5Dem
VjaCBSZXB1YmxpYzg5QAE=;X-APPLE-RADIUS=49.91306615921171;X-APPLE-REFERENC
EFRAME=0;X-TITLE="Ondříčkova 22":geo:50.079930,14.451485
UID:FAD11C9E-0EAB-47E3-91E0-E97CDF4CD926
DTSTAMP:20171201T104202Z
LOCATION:Ondříčkova 22\nPrague, Czech Republic
URL;VALUE=URI:
SEQUENCE:0
SUMMARY:Leo
LAST-MODIFIED:20171129T165619Z
CREATED:20171129T165619Z
DTSTART;TZID=Europe/Prague:20171201T120000
END:VEVENT

Start by reproducing the subscription failure with the provided iCloud event, especially the folded X-APPLE-STRUCTURED-LOCATION content, and trace the calendar subscription parsing path that reports the ParseException. Compare the event with the iCalendar conventions expected by the parser. Done means the supplied iCloud calendar imports successfully without a parsing error.