Calendar Export : Skipping calendar containing invalid calendar data

How to use GitHub

• Please use the 👍 reaction to show that you are affected by the same issue.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Steps to reproduce

1. php occ user:export USERNAME /tmp/ -t calendar -vvv
   Defaulted container "app" out of: app, web
   Exporting user information in user.json…
   Exporting settings in settings.json…
   Exporting versions in versions.json…
   Exporting calendars into dav/calendars/…
   Skipping calendar "USERNAME" containing invalid calendar data
   Skipping calendar "Anniversaires des contacts" containing invalid calendar data
   Skip non-selected migrator: contacts
   Skip non-selected migrator: trashbin
   Skip non-selected migrator: forms
   Skip non-selected migrator: passwords
   Skip non-selected migrator: account
   Skip non-selected migrator: files
   Export saved in /tmp/USERNAME_2024-10-21_09-27-55.zip

Expected behavior

Calendar should be exported successfully.

Actual behavior

1. Failing to export calendar with error "containing invalid calendar data" : It doesn't explain which data is invalid and why.
2. Even with '-vvv' option, log is not more verbose.

The export of this same calendar in web (through the UI in calendar app) works well.

Server configuration

Web server: Nginx

Database: PostgreSQL

PHP version: 8.2.23

Nextcloud version: 28.0.10

Start by reproducing the issue with php occ user:export USERNAME /tmp/ -t calendar -vvv and compare the command output with a calendar export from the web UI. Trace the calendar export entry point and the validation path responsible for the “invalid calendar data” message. Done means the failing data and reason are identified in the output, and verbose mode provides additional diagnostic detail.