Calendar sync with Thunderbird/Lightning broken due to Apache 2.4/http2?

My nextcloud server (back then it was still running ownCloud) stopped syncing calendars with Thunderbird/Lightning a few weeks ago. Now I just learned, that my hosting provider (Hostpoint) upgraded from Apache 2.2 to Apache 2.4 which now supports http2. This upgrade seems to be what broke the sync.

Is there something I can do on the nextcloud server side to get the sync working again?

I have also added a comment to an existing bugreport for thunderbird (https://bugzilla.mozilla.org/show_bug.cgi?id=1106727). As the sync works with Android and iOS devices still works, TB certainly is also involved in this issue.

The nextcloud server is the latest version. TB/Lightning as well. Tested with Windows and Linux (Kubuntu 16.04LTS)

Iā€™m doing just fine here with Apache 2.4.10 and the latest Thunderbird/Lightning on Win10. I know this isnā€™t particularly useful information for you, but maybe itā€™s a different part of the stack thatā€™s causing the problem?

Thanks for the info. Iā€™m still trying to figure out what the exact problem actually is. All I know for sure is, that it stopped working, when my provider upgraded Apache.
Any help in finding the real problem is appreciated.

Iā€™m having the same issue.
The Thunderbird console tells me this:

CalDAV: Nexcloud points to a DAV resource, but not a CalDAV calendar

This reminded me of an old bug report where Lightning does not support multiple calendars and so I tried to set up individual calendars and that worksā€¦
You need to click on the calendar you want to add to TB, which brings up a menu and click on share to get the URL to use.

I have the same issue with Caldav and Carddav as well. I also made a post here. Unfortunatly your solution does not fix my problemā€¦

In my case this is not the issue since Iā€™m using the individual calendar links from ownCloud/nextcloud. And it had been working for several years like this before!

Did you find a solution yet? Iā€™m facing the same issue. All windows clients with Thunderbird show the login window, but wonā€™t accept any correct credentials. NC logs doesnā€™t seem to say anything unusualā€¦

No still no solution foundā€¦ :frowning:

Hi,

Works well hereā€¦

Donā€™t forget to write the complete url of your calendar in Thunderbird/Lightning

https://your-server/remote.php/dav/calendars/your-user-name/name-of-the-calendar/
and
https://your-server/remote.php/dav/calendars/your-user-name/contact_birthdays/

Yes, Iā€™m using the full URL. And it used to work for many years actually. But since my provider updated to http2 it does not work anymore with Thunderbird/Lightning but all other clients still work.

O.K. meanwhile be sure that the openssl library version is = 1.0.2 or greater.
The1.0.2 version include specification RFC7301 (protocol ALPN) required for being able to accept HTTP/2 negociations.
The 1.0.1 version permit only NPN protocol wich is now obsolete.

[user@server:~] $ openssl version
OpenSSL 1.0.2h 3 May 2016

The OpenSSL version on the server seems to be OK. Any other ideas?

Sorry, noā€¦

I know some administrators have been obliged to tweak their ciphers (no cipher from a specified black list may be used) but i didnā€™t have to do that here. Anyway must be a problem with your hosting provider.

Regards,

ā€¦ or rather TB/Lightning as it works with all other clients I have tested.
But thank you anyway!

If others also face this problem please comment on this Bug report https://bugzilla.mozilla.org/show_bug.cgi?id=1106727

I have to correct myself: The issue was that two users obviously didnā€™t enter their passwords correctly, although they were 100% sure they did. The question remains, why Lightning wants them to reenter their credentials after migration, but anyways, it works now.

Sorry to barge in on this thread and I hope youā€™ll find a solution soon! :sweat_smile:

It is also important to create the url be in lowercase format.

Same problem on nginx. Interestingly, additionally to calendar not syncing, I canā€™t access Nextcloud from Opera Mobile with http2 enabled.

I have the same problem, since I switched my server to http/2.

Actually I was hoping that adding it with Protocols h2 h2c http/1.1 would allow it to fall back to http/1.1 if http/2 is not working. But I also enabled H2Direct, which I read brings some compatibility issues. I will try it without and see if it helps. But it will take time until tomorrow. My preview generator is still pre-generating previews of dozens GB of pictures :stuck_out_tongue: .

Opera Mini actually works fine for me, with and without data compression (inaktiv while WLAN connection). I use the newest beta 21.0.2254, maybe they added support recently.

http://caniuse.com/#feat=http2 shows browser compatibility. Opera Mini is still listed as unsupported. Maybe this changed in the current beta, maybe it just works because of successful http/1.1 fall-back?

ā‚¬: disable H2Direct directive doesnā€™t fix the thunderbird issue. I also updated thunderbird and lightning to the current beta (50 beta 3) but still no http2 support. Poor thingā€¦ maybe someone with access to mozilla forums can give some hint there.

ā‚¬ā‚¬: Okay, the latest issue was just because of the calender cache could not be touched or something. I deleted to old ones and added the exactly same DAV urls again and now it works. Also the contacts now work, why ever :smiley: . I donā€™t know if this is new, but at least in the thunderbird 50 beta there is also some setting in about:config to enable/disable SPDY and http2 suppoert.

I finally found a workaround and got Thunderbird/Lightning got to sync again with nextcloud
The workaround is to set ā€œnetwork.http.spdy.enabled.http2ā€ to false in the Thunderbird config.
See also https://bugzilla.mozilla.org/show_bug.cgi?id=1106727#c18

As additional information here is a Bug report against Apache for this issue https://bz.apache.org/bugzilla/show_bug.cgi?id=60663

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