CalDAV Invitations & Events in Thunderbird/Lightning

Evan L

Jan 14, 2019
Virginia, USA
cPanel Access Level
Website Owner
New thread on the same topic from 2017:
Invitations and Events in Thunderbird/Lightning with cPanel CalDAV

I am seeing the same issue with:
* cPanel 76.0.17
* Thunderbird 60.4
* Lightning 6.24

All with email accounts & CalDAV calendars on our domain - hosted by cPanel.

1, User sends me a calendar invite (they are the owner of the meeting)
2. I accept the calendar invite
3. Thunderbird switches the owner of the meeting to me
4. I automatically receive an invite email from myself

Has there been any progress on this since 2017? The thread above links to some suggested bug fixes in Horde and Thunderbird.

Anyone have a workaround that works with Thunderbird?

Evan L

Jan 14, 2019
Virginia, USA
cPanel Access Level
Website Owner
Hi Lauren,

Yes, this an open issue for me. (I discovered it after resolving the prior one).

Seems like the solution from 2017 was to use the Horde web client for accepting meeting invites. I'm wondering if anyone has found a better workaround (ideally something that works with Thunderbird).



Staff member
Apr 11, 2011
Hello @Evan L,

cPanel & WHM version 76 includes a version of Horde with the patch/fix noted on the following Horde bug report:

Tickets :: [#13664] accept event to Horde CalDAV calendar from Thunderbird Lightning parses Attendees

However, as noted in the recent comments on the above Horde bug report, the patch provided by Horde does not fully solve the issue. I recommend opening a new bug report with Horde that includes the step-by-step instructions of how you are reproducing the issue.

I do want to point out that we are exploring the addition of a new plugin for cPanel & WHM version 80 that will add support for CCS. It's still tentative, but we should know in the next couple of weeks if this will make it's way into the product as a plugin in version 80. I'll update this thread with more information as it becomes available.

Thank you.


Dec 19, 2019
New York
cPanel Access Level
Website Owner
Hi. My server is running
cPanel Version82.0 (build 16)

I believe I'm running Horde Groupware 5.2.22

I'm having the same issues that when I accept a calendar invite using a caldav connection, it always recreates the appointment and sends it back to the original meeting organizer as if I sent out the meeting.

It does not behave that way if I accept the meeting within Horde.

What do I need to do to correct this behavior.



Here is the text that it sends out.

[email protected] wants to notify you about changes in "Test appointment".
Start:12/19/2019 9:00 am
End:12/19/2019 9:59 am
Summary:Test appointment
Please do not edit this section of the description.

View your event at
Google Calendar EDITED:~:~:~:~:~:~:~:~:~:~:~:~:~:~::~:~::-
[email protected]Required ParticipantAccepted
[email protected]Required ParticipantAccepted
Possible Conflicts:
Last edited by a moderator: