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I am currently using Thunderbird, I can successfully send meeting requests to all types of calendars however when someone sends me a meeting request and I want to either accept or decline the meeting error number: MODIFICATION_Failed appears. I have also installed Lightning 0.9 but the same error is repeating

Any ideas? Inge

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not a dupe, he wanted them automatically added to calendar. OP on this question can't even accept requests. – John T Oct 6 '09 at 15:46

This is a known bug which has recently fixed, you can find details on it here. The most recent version of lightning will fix this (See Systech's answer for links).

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I had this problem, i downloaded the beta versions and this seems to solve the problem

Thunderbird 3 Beta 3:

Lightning 1.0pre: (Warning: This is a development snapshot: It contains the latest changes, but may also have severe known issues, including data loss situations. In fact, it may not work at all.

Source <>

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You may want to reference your source:… – John T Oct 6 '09 at 15:49
@ John T This has been updated – admintech Oct 6 '09 at 15:53

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