That implies that it is one of the add-ons causing the error message. to find out which one follow the procedure in the troubleshooting extensions and themes article.

If you have "ask toolbar" installed, uninstalled it. Most users have the same problem with this add-on.

I do not have the "ask toolbar" installed.

However, the issue was fixed when I reinstalled/updated Firefox Personas manually.

Hopefully it won't arise again.