This error had plagued me for some time, but the chrome plugin worked… so I didnt mind until I updated to a full 64bit OS, and the chrome plugin does not exist for 64bit
Turns out that the plugin was trying to read the firefox preferences but fails on two accounts, it apparently doesnt handle spaces or relative paths..
Change ~/.mozilla/firefox/profiles.ini something like this:
[General] StartWithLastProfile=1 [Profile0] Name=default IsRelative=0 Path=/home/user/.firefox/default/187x6ax2.slt
to
[General] StartWithLastProfile=1 [Profile0] Name=default IsRelative=1 Path=187x6ax2.slt
and then
ln -s ~/.firefox/default/187x6ax2.slt ~/.mozilla/firefox/