Short tip: Nextcloud + 2FA + CalDAV and CardDAV under iOS

Error message when setting up the calendar

While setting up my Nextcloud calendar on an iOS device the other day, I encountered the following error:

1CalDAV account verification failed

The error also affected contacts via CardDav - the usual troubleshooting options failed:

  • Password reset
  • Using another device
  • Use different URL and port combinations

Finally, I created another new user, which worked without problems - that's when I noticed that 2FA is also a potential source of errors. In fact, iOS devices seem to have problems here - I don't recall a similar error on an Android device, my memory may be wrong here.

Disabling 2FA (and re-enabling it after configuration) was not an option. Fortunately, Nextcloud has offered the option to create so-called app passwords for some time now. These are used for authentication for certain applications (e.g. Cal-/CardDAV) without 2FA. During creation, a sufficiently long key is generated and displayed once. Further details can be found in the Nextcloud documentation.

Definition of an app password without file system access

So the solution was quite trivial in the end: a new key can be created in the personal security settings - ideally without file system access. I defined the key when configuring the calendar - and the calendar worked.