Thunderbird Calender and Tasks Sync not working


I am using Thunderbird 102.9.1 on my Desktop PC and on my Notebook. I recently installed W11 on my notebook and set everything up again. This then made me realize that I don’t need addons like TbSync etc at all. I can also just add a calendar with a web address and then see my calendar and tasks (WebDav). I then changed this on my desktop PC as well. But now nothing seems to work. Calendars are not synced and the tasks are not correct. I see only old tasks, which have long been deleted via smartphone. I also opened Nextcloud on the web to see if the tasks were really synced successfully from the smartphone to Nextcloud. And there everything fits. Everything is perfect.

I have also manually clicked sync on the notebook and on the computer. But nothing changes. But there is also no error message to see. By the way, the calendars were added via App Token. And when I click on sync I can see the Thunderbird instance was connected to my Nextcloud. But no data changed. But when I create a new calender event on my PC or Notebook, then it will be syned with my Nextcloud and I can see it on my phone. So they can upload new events, but they cant download… I dont understand this.

I found this: Thunderbird 60 problems with Address and Calendar Sync
But I think its not working for Thunderbird 102. I can’t find this settings.

The adressbook sync work good with CardBook. I think this is the best way to sync my contacts?


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Still not working. Thunderbird shows me always random tasks I deleted in the past. Nextcloud Web and Smartphone is working fine. Such a bullshit. So it is not possible to use Nextcloud with the WebDav Thunderbird connection? You guys all use Tbsync or similar software?

No one use Nextcloud with Thunderbird?

I had it working on my computer. I can’t check right now, if it is still working (not at home).

I’d check when you open TB, if it is able to read from the server. Check the logfiles, if it gets 4xx or 5xx status which might indicate some problem with the links to caldav. I had issues on iOS devices when the service discovery wasn’t set up correctly.

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I am having this same issue. I see old tasks in Thunderbird, but tasks today and in the future do not show up in Thunderbird. There is nothing in my log files relating to this issue. Depending on the version of TB you use, Tbsync shouldn’t be necessary - from what I understand. I don’t currently use it.

EDIT: For what it’s worth, I have a separate desktop calendar app that I recently began using (because I find it more reliable than the TB calendar) and all tasks sync there without any problems.

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Thanks for your input. I think it is a issue with the Offline Support. You can enable it in the Thnderbird calendar settings. If enabled, old task are still there, even when you have deleted them from your phone. Because the offline storage of the Thunderbird calendar will not sync. Now I disabled offline support and its working fine. But this not a good solution. I still want to have my calendar, when I am offline. Lets see. Maybe it will be fixed soon by the Thunderbird team…


Thanks for your suggestion. I will see if that works for me too.

This fixed the same problem for me (calendar not syncing) for Thunderbird 102.12.0 (32-bit) Windows.

With Provider for CalDAV & CardDAV :: Add-ons for Thunderbird everything worked fine.

I know. I used it before. But I don’t want to use any addons. It should also work with the features of Thunderbird.

I am curious to know if you solved your sync problems, because I face the exact same. I have a W10 laptop and my calendars are synced (or supposed to) with a Nextcloud account (version 27). I also sync the calendars with Dav5x on an Android smartphone. The calendars on the server are up to date, but on my laptop they don’t sync. More precisely, all events appear on the server, whatever client where I created them, but afterwards what is on the server does not appear on my Thunderbird calendar. Everytime I have to “disconnect” from my remote calendar and add it again.
Maybe a clue: in the “Nextcloud” folder on my laptop, there is a “Calendar” folder, which is empty.
Any idea ? Could it be due to Nextcloud, more than to Thunderbird ?
Thanks a lot.

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