Nextcloud Tasks/Calendar: Hidden limit of 30 calendars causes "unable to create the list" error

[marcusquinn]

Problem

When using the Nextcloud Tasks app, attempting to create a new task list fails with: "An error occurred, unable to create the list."

Creating tasks via Apple Reminders (CalDAV sync) also silently fails — new lists simply disappear.

Deleting existing task lists and emptying the trash temporarily fixes the issue, but it returns once you have enough lists again.

Root Cause

Nextcloud 32.x introduced a RateLimitingPlugin in the DAV app (apps/dav/lib/CalDAV/Security/RateLimitingPlugin.php) that enforces a hard limit of 30 calendars + subscriptions per user via the dav.maximumCalendarsSubscriptions app config setting (default: 30).

Two issues with this limit:

1. The default of 30 is too low for users who use the Tasks app heavily (e.g., project management with one task list per project). Each task list is a CalDAV calendar, so 28 project lists + a personal calendar + a birthday calendar = 30 = limit reached.
2. Trashed calendars count toward the limit. The getCalendarsForUserCount() method in CalDavBackend.php has no deleted_at filter, so calendars in the trash still count. This is arguably a bug — trashed items shouldn't block creation of new ones.

There's also a rate limit of 10 calendar creations per hour (dav.rateLimitCalendarCreation), which can be hit when setting up multiple projects.

Fix

Increase the calendar+subscription limit (default: 30)

occ config:app:set dav maximumCalendarsSubscriptions --value=999

Or disable the limit entirely

occ config:app:set dav maximumCalendarsSubscriptions --value=-1

Optionally increase the rate limit (default: 10 per hour)

occ config:app:set dav rateLimitCalendarCreation --value=50
Suggestion for Cloudron
Consider either:

• Increasing the default maximumCalendarsSubscriptions to 999 in the Cloudron Nextcloud package's start.sh
• Or documenting this limit in the Cloudron Nextcloud docs
  The error message from the Tasks app ("An error occurred, unable to create the list") gives no indication that a calendar limit has been reached, making this very difficult to diagnose.

Environment: Cloudron Nextcloud package 5.6.7 (Nextcloud 32.0.6), Tasks app 0.17.1