Syncing weirdness

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Syncing weirdness

DS218, DS213+, DS213
Operating system
  1. Linux
  2. Windows
Mobile operating system
  1. iOS
Anyone ever came across the following issue & have a solution? I'm using Synology Calendar (DS218, DSM 7.1-42661 Update 4) as my central calendar.

I'm using two clients: (1) iPhone 13 (iOS 15.7). (2) Thunderbird (102.3.0 under debian 11).

Both clients sync correctly... except for this effect: I create a new appointment in Thunderbird, and sync it to the Syno. I then edit that appointment under Thunderbird. Then I sync again. After that sync all edits are lost. So it is as if the entry is "read only" on the Synology Calendar. And, yes, I have not made my Syno Calendar "read only".

Now when I edit the same entry under iOS, sync that edit back, the edit does sync correctly. So that works as expected.

But the really strange behaviour is this: after editing the appointment under iOS and synching that edit back to the Syno, any edits to that appointment under Thunderbird suddenly sync correctly.

So, in effect, an appointment is "read only" under Thunderbird until I edit it under iOS, which seems to "unlock" it for further editing under Thunderbird somehow.

I feel this symptom most likely reflects a problem on the Synology side. Thanks for any pointer!
I feel this symptom most likely reflects a problem on the Synology side. Thanks for any pointer!
Welcome to the forum!

Not sure I would be so quick to draw that conclusion as while personally I do not use Thunderbird, I have not found a single problem running the cal among multiple iOS and macOS devices. Any sync in any direction/device is running as expected.
Fair enough, thanks for that feedback. Still, I was trying to poll whether anyone has seen the same or similar issues. That might help me narrow down the source of the problem.
Last edited:
There's a RO checkbox in Tbird. Did you uncheck that?


Are you using a Tbird addon for that?
Hi Telos, thanks for looking at my question. No I didn't check that "read-only" box in the TB calendar configuration. I'm not using a TB addon either, just the built-in TB syncing functionality.

The strange thing is that everything "works" with a given calendar entry as long as I have once touched that entry through the iOS client. So it's unlikely to be a wrong setting I think.

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