# Can't get Thunderbird to sync calendar/contacts w/ Nextcloud

**URL:** <https://help.nextcloud.com/t/cant-get-thunderbird-to-sync-calendar-contacts-w-nextcloud/226308>\
**Category:** ℹ️ Support\
**Tags:** caddy, docker, caldav, setup\_warning\_wellknown, nc31, calendar-app\
**Created:** [June 4, 2025, 5:24pm UTC](https://help.nextcloud.com/t/cant-get-thunderbird-to-sync-calendar-contacts-w-nextcloud/226308 "2025-06-04T17:24:04Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![mdiehl](https://help.nextcloud.com/letter_avatar/mdiehl/32/6_22734026db12803ebb3e059622ac3534.png) [@mdiehl](https://help.nextcloud.com/u/mdiehl)\
**Post date:** [June 10, 2025, 7:58pm UTC](https://help.nextcloud.com/t/cant-get-thunderbird-to-sync-calendar-contacts-w-nextcloud/226308/3 "2025-06-10T19:58:12Z")

</div>

Alright, I’m going to post the requested info from the [Support Template](https://help.nextcloud.com/t/support-template-please-use-this-when-you-request-support/137402). Sorry about not doing it “right” the first time. 😀

Here we go:

I’m having difficulty getting Thunderbird to sync to my NC calendar and contacts.

I’ve attempted to point Thunderbird to my NC calendar as:

[https://nextcloud.example.com/remote.php/caldav](https://nextcloud.example.com/remote.php/caldav) (redacted)

Thunderbird reports that it can’t find any calendars. When I point a browser at that url, I get a blank screen.

When I go to NC’s admin/overview screen, I see:

There are some errors regarding your setup.

> - Your web server is not yet properly set up to allow file synchronization, because the WebDAV interface seems to be broken. To allow this check to run you have to make sure that your Web server can connect to itself. Therefore it must be able to resolve and connect to at least one of its `trusted_domains` or the `overwrite.cli.url`. This failure may be the result of a server-side DNS mismatch or outbound firewall rule.
> - Your web server is not properly set up to resolve `.well-known` URLs, failed on: `/.well-known/caldav` For more details see the [documentation ↗](https://docs.nextcloud.com/server/31/go.php?to=admin-setup-well-known-URL).

I don’t see any interesting log entries in any of the containers.

I guess I need to explore what the “trusted\_domains” setting is, and where to set it. Any guidance on that and any further troubleshooting help would be most appreciated.

**So, here is the extra information you asked for:**

I’m using **[Nextcloud Hub 10](https://nextcloud.com) (31.0.4)** in a Docker container.  
The host is running “24.10 (Oracular Oriole)”.  
I’m using Caddy 2.6.2 as the reverse proxy.

Here is the applicable caddy config entry: (redacted)

[https://nextcloud.example.com](https://nextcloud.example.com) {  
tls [mdiehl@example.com](mailto:mdiehl@example.com)  
reverse\_proxy 192.168.1.15:11000  
}

I’ve had this working before, but I had a hard drive failure and had to rebuild. But I rebuilt with the same script that I used to build it the first time.

sudo docker run   
–init   
–sig-proxy=false   
–name nextcloud-aio-mastercontainer   
–restart always   
–publish 8080:8080   
–env APACHE\_PORT=11000   
–env APACHE\_IP\_BINDING=0.0.0.0   
–env APACHE\_ADDITIONAL\_NETWORK=“”   
–env SKIP\_DOMAIN\_VALIDATION=false   
–env NEXTCLOUD\_DATADIR=“/home/shared/Containers/NextCloud”   
–volume nextcloud\_aio\_mastercontainer:/mnt/docker-aio-config   
–volume /var/run/docker.sock:/var/run/docker.sock:ro   
nextcloud/all-in-one:latest

My environment is behind Cloudflare, fyi.

Any advise you can give me would be most appreciated. And once again, thank you for your time.

Mike.

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_[View the full topic](https://help.nextcloud.com/t/cant-get-thunderbird-to-sync-calendar-contacts-w-nextcloud/226308)._