If you are like me and heavily use several Firefox add-ons, chances are that Gmail Manager is one of them. It is a great add-on to manage multiple Gmail accounts (as the name implies).
However, with the latest Firefox update (v. 6.0.2) it broke and wouldn’t login.
No worries, after a bit of searching I came across a solution that worked for me.
In Firefox, go to
https://github.com/downloads/athomas/mozilla-firefox-addons/gmail_manager-0.6.4.1.3-fx+sm.xpi
when asked restart your web browser and the Gmail Manager add-on should work once again.
Updated on 12/22/11 for Firefox 9.0.1: https://github.com/downloads/athomas/mozilla-firefox-addons/gmail_manager-0.6.4.1.5-fx+sm.xpi