Accept and Decline button missing in thunderbird when receiving an invitation

I use a Google Calendar with Thunderbird/Lightning and I have always been able to Accept invitations through Thunderbird.

I recently lost the Accept/Decline buttons and just figured out the problem. I had recently added a shared iCloud calendar, and the new calendar was automatically associated with the same email address as the Google calendar.

All I had to do is set the iCloud calendar to not be associated with my email address, and my Accept/Decline buttons came back.

In the current version (0.18 with lightning 1.9.1), this is a hidden feature which is disabled by default. It is slightly buggy, but works sufficiently to just get an invitation into your google calendar from your (possibly non-google) inbox.

Using the config editor, simply set calendar.google.enableEmailInvitations to true. You may also want to set calendar.google.sendEventNotifications to false to avoid the possibility of an old bug that sent new events instead of notifications; I've not tested this. Then, restart thunderbird.

Once you have done this, in the properties of your google calendar, you will have the option to associate it with an account.

If it still does not work, try deleting and reconnecting your calendar via the xml-address from the Google Calendar website.

After you do that, you will get the appropriate buttons (they will appear with a brief delay as your google calendar is checked to see if the event exists). If it doesn't, you can use the accept/decline/tentative buttons as with other calendar types.

One bug that currently exists is that if the event is in your calendar already, you will get an update button whether there is any change or not. The button will usually cause an error if pushed.

I've suffered the same symptoms but with the following configuration:

• Windows 7 Enterprise
• Thunderbird 24.5.0
• Lightning 2.6.5
• No Google Calendar plug-in
• A few webcal calendars plus a couple of local moz-storage-calendar calendars

After a few wild goose chases, this solved it for me:

1. For all non-editable calendars, change Properties->Email to "None"
2. For all editable calendars, set Properties->Email to your email account.

Boom, buttons suddenly appear. For me it seemed that have a Read Only calendar with an email set was preventing the buttons from appearing. I'm not sure what the trigger was - one day it was working then it wasn't. Nothing relevant appears in the error console.