Rated 4 out of 5 stars

For me it worked fine too till FF45 Update came out. Could the author please patch this so it works again?

Đánh giá này là cho một phiên bản trước của tiện ích (1.7.5.1-signed). 

This bug should be fixed in 1.7.6 version, released now.
A workaround is to set the preference "extensions.profileswitcher.use_onbeforeunload" to false, but I suggest to try before the new version.