Lightning w/Google Calendar: Can't accept invitation

For discussing the Mozilla Calendar, Sunbird and Lightning projects.
Posts: 18
Joined: March 27th, 2006, 11:31 am

Post Posted February 25th, 2009, 6:39 pm

Since my workplace doesn't use Exchange, I am using Thunderbird/Lightning with my Google Calendar, then using Google's ActiveSync capability to push calendar events to my smartphone. However, when I receive an invitation at my work address, I'm not able to accept it into my Google Calendar. I'm guessing this has something to do with the fact that the email addresses don't match (my work email address is not my gmail address). Is there any way around this?

In the meantime I have been forwarding the invitations to my gmail account, and accepting them in gmail. This seems to be getting the job done, but it would be nice if I didn't need to take that extra step.

Posts: 9
Joined: March 2nd, 2009, 2:12 pm

Post Posted March 2nd, 2009, 4:14 pm

Check the following:
1. The e-mail account on your calendar (is selected when the calendar is being created) is the one receiving the invites (sometimes 'None' is selected).
2. Read the contents of the extension's prefs.js file:

* Invitations and notifications.
* Note that if enableEmailInvitations is enabled it is a good idea to disable
* attendees or at least sending event notifications.
pref("", true);
pref("", true);
pref("", false);

To change this values go to Properties->Advanced->ConfigEditor


Posts: 18
Joined: March 27th, 2006, 11:31 am

Post Posted March 3rd, 2009, 7:41 am

I don't think an email account for the calendar was selected when I created it. This is a Google Calendar, and I added it using the provider extension for Google Calendar.

As for the preferences.js file, the values are just as displayed above.

I also don't know what you mean by "Properties->Advanced->ConfigEditor", can you be more specific?

Posts: 1
Joined: March 4th, 2009, 8:56 am

Post Posted March 4th, 2009, 9:00 am

just so you know, you no longer need to use the provider extension with lightning 0.9. You just have to add your calendar to Thunderbird using the CalDAV support. Here are the instructions ( ... 58#sunbird)

To set up CalDAV support for Google Calendar in Mozilla Sunbird, follow these steps:

1. Open the Sunbird application and select File > New Calendar.
2. Select On the Network and click Next.
3. Select the CalDAV format option.
4. In the Location field, enter [ [ your Google Calendar email address ] /events ] and click Next.

For example, if the email address used to access your Google Calendar is, the Location field should contain ... com/events
Be sure to use https in your URL, as an http address will not work.

5. Enter a name and select a color for your calendar.
6. In the pop-up screen, enter the following information:

Username: This is the complete email address you use with Google Calendar (including the part after the @ sign). If you're using Google Apps, be sure to enter your Google Apps email address.
Password: This is the password you use to sign in to Google Calendar
7. Click OK.

Your Google Calendar will now appear in the Calendar tab of Mozilla Sunbird, and Sunbird will sync any changes to and from Google Calendar.

Posts: 18
Joined: March 27th, 2006, 11:31 am

Post Posted March 4th, 2009, 9:47 am

OK, I added the calendar using the CalDAV instructions, but I'm getting a MODIFICATION FAILED error whenever I try to accept an invite, and then the calendar is unavailable until I restart Thunderbird.

Again, I don't manage my Gmail account using Thunderbird, so the email address associated with the calendar in Thunderbird is my work email. Is this what could be causing the problem?

Posts: 1
Joined: May 11th, 2009, 9:57 am

Post Posted May 11th, 2009, 10:07 am

I'm having this issue too. Can someone help?

Posts: 9
Joined: May 25th, 2004, 8:30 am

Post Posted June 5th, 2009, 5:51 am

I am having this issue as well. Does anyone know how to fix this?

When accepting an invitation to my Google Calendar I get an error MODIFICATION_FAILED.


Posts: 9
Joined: May 25th, 2004, 8:30 am

Post Posted June 13th, 2009, 7:19 am

I was able to get this working by installing the Thunderbird add on "Provider for Google Calendar". You can get it here:

I don't get the Modification Failed notice any more and I can accept invitations. When I accept an invitation or add an event to my calendar they get added to my Google calendar almost immediately. I'm using Pocket Informant on my iPhone and have it set to sync with my Google calendar and my Informant calendar gets updated right away. The same goes for when I add an event to my iPhone and sync it to my Google Calendar it shows up in my Lightning calendar.

Posts: 2
Joined: August 5th, 2009, 4:26 pm

Post Posted August 5th, 2009, 4:28 pm

I actually still have this exact same problem. I have tried with CalDav support and the plug in. If I use the plug in, it just does not allow me to accept calendar invites, if I use the CalDav, I get the same error as above and it will not update. The odd thing is, I can add a calendar event manually into either without problem. The issue is only with accepting invites.

Any ideas?

Posts: 2
Joined: August 5th, 2009, 4:26 pm

Post Posted August 5th, 2009, 4:36 pm

I think I have found it -- I deleted my CalDav account and used the one created as part of the plug in. Then, I used the config editor to set pref(" to true -- then edited the calendar that I had created and it allowed me to select a calendar to bind it to, and it appears to work!

Posts: 5
Joined: April 13th, 2004, 2:54 pm
Location: Huntsville, AL

Post Posted November 10th, 2010, 12:03 pm

Fixed mostly the same way, but did not delete anything
Used config editor and changed "yes"
Restarted TB
Right clicked Google Calendar and selected properties
Under properties there was a new choice for e-mail and I selected the email address I wished to add invites from.
Worked great

I am using provider for Google Calendar
Mark Bannister

Posts: 1
Joined: November 22nd, 2010, 1:45 am

Post Posted November 22nd, 2010, 1:52 am

Thanks Mark did the same thing and worked well ! Good solution ! =D>

Posts: 2
Joined: March 2nd, 2011, 3:02 am

Post Posted March 5th, 2011, 11:38 am

Hi ,

After creating and event invitation and accepting it by a invitee, the response i.e., accepted/declined/tentative does not reflect in the reply mail. However, the response briefly appears in the pop-up onthe lower right hand corner when the mail arrives. Can this be made to be part of the mail also ?

Version of Thunderbird : 3.0.3, 3.1.7, 3.1.8
Lightning : 1.0b1rc1, 1.0b2


New Member
Posts: 1
Joined: April 14th, 2011, 11:24 am

Post Posted April 14th, 2011, 11:35 am


I am working on getting Thunderbird/Lightning working as a client to connect to our Google Apps accounts.
Most of it is working ok but Thunderbird/Lightning does not allow me to accept invites.

Thunderbird v3.1.9
Lightning v1.0b2
Provider for Google Calendar v0.7.1

I have tried the above suggestion (by markbannister above) and now Thunderbird recognizes the invite and I get the accept/decline buttons but I receive a MODIFICATION_FAILED error when I click one of the options.

I will try this without Provider enabled and post the results here.

thanks for any suggestions,


New Member
Posts: 1
Joined: April 28th, 2011, 10:21 am

Post Posted April 28th, 2011, 10:37 am

This thread is great. I had the same problem accepting and did the steps above, except I also had to delete the default Lightning calendar called "Home". Now I can accept invitations into my google calendar.

EXCEPT, now each new event is being sent again to all attendees but from me as the originator. After accepting each event I opened each and added a reminder (that's another issue), and then the event started being sent to each of the attendees as a new event from me.

Another thing that is happening is that my google calender keeps getting reset as ReadOnly!

I had to delete all new events that I accepted to stop it from resending itself continuously. One person has accepted my new duplicate event about 3 times before I killed the events.

Anyone have any suggestions? I've got Lightning and the Provider for Google Calendar add-ons. Working goodup until now except for some random errors.

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