From: jkosonen's blog

Error using fMobi at the moment
Posted on October 1, 2012 by jkosonen
There are somekind of limit reached with Facebook API, or FB API is returning “Application limit reached” to every API call, so that is why fMobi is not working at the moment, but just returning Facebook error. I have no idea what that limit is or when it is cleared, hopefully soon. Until that I’m clueless what to do. Hopefully everything sorts out well soon.

I know this is very bad to you guys, but believe me, it’s very bad to me too.

Apologies, but yet again, this is something that I did not cause and only FB has the solution