Attached is a single VEVENT that causes "Datetime has no timezone or viewer timezone." in the calendar view after importing, the import itself runs fine.

Getting Datetime has no timezone or viewer timezone when viewing the main calendar.(https://gist.github.com/carlokok/570d524fe2a6dd1472835c0fa67b7faf) after import. Since the import contains a quite a bit of private data, how can I narrow down which record specifically it fails on?

It makes sense in retrospect, but not from the workflow no.

My apologies. I read over that bit and presumed it meant edit the calendar items

In T11816#202107, @epriestley wrote:

Everyone can see from which url a calendar event came.

This isn't expected. Can you give me reproduction steps for this?

My only concern with the current ics importing is that the url for importing from google, owncloud/nextcloud usually contains secrets other users shouldn't see, like in the case of owncloud: un/pw. Everyone can see from which url a calendar event came.

Right. This was a feature request to have "ctrl+enter" (or cmd enter on osx) to work in all fields (in addition to enter in the fields where it makes sense), so that there's 1 key that always works to submit the current form.