I cannot tell you which version of Thunderbird, because one of the problems is that the "Options" feature no longer works, along with a laundry list of other problems. The update was automatically downloaded and installed on March 8, 2016. I tried to re-install a fresh build, downloaded on March 9, 2016, overtop of my existing build. Installation appeared to work, but did not fix any of the problems. Windows 10 Home, version 1511, OS Build 10586.122. Problems: - cannot view the Inbox or any other folders for any of my accounts (although they can be opened in New Tab) - cannot reply, reply-all or forward any messages (buttons and selection from context menu do not respond) - cannot create a new email (button does not respond, selection from File menu does not respond) - Options screen and most other setting screens will not open (selections from Tools menu do not respond) - etc., etc. (too many issues to list) Thank you for your consideration.