Comment 1 for bug 795766

Same here. Works fine on firefox < 5.0 on both win and ubuntu and after update to 5.0 it says that the password is wrong.
I don't use the mozilla but the minimal wave server [1] on my own machine.
Don't know if mozilla changed something in the password hashing algorithm, but it's really annoying because I use firefox sync really often to sync my bookmarks and tabs between various systems and os'es.

[1] http://tobyelliott.wordpress.com/2009/09/11/weave-minimal-server/