User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:188.8.131.52) Gecko/20080201 Firefox/184.108.40.206 Build Identifier: Thunderbird 220.127.116.11 My older version of Thunderbird attempted an automatic update yet could not update all files. After multiple attempts, I uninstalled and began installing build 18.104.22.168 from scratch. I received the following message: "Error opening file for writing", that file being mozmapi32.dll. To make matter worse, i am unable to delete the Thunderbird files already written to my hard drive by the faulty installation. If I try, I get the message that mozmapi32.dll cannot be deleted. If I attempt to reinstall on top of the remaining files, I once more get that this file cannot be opened for writing. I have unchecked "read only" but this has not helped. Help! Reproducible: Always Steps to Reproduce: 1. 2. 3.
Judging by the duplicates of the update bug (bug 340535) and of the various installer bugs, 90% chance that it's quickcam, the software for a logitech webcam, that has mozmapi32.dll locked, and shutting that down will let you install/update. If not, someone in any of the support channels in http://www.mozilla.org/support/thunderbird/forums should be able to help you track it down, or sneak around it by installing in a different directory.
I had this problem, and it was the web cam. Shutting the web cam down, solved the problem.