incompatable assets

has anyone had this before, you go into online, spawned in a lobby with only you there, try to join another session or friends/ crew session and you cant because it says you have incompatable assets......

if you are using any mods which include editing update.rpf files through open iv you cant join anyones session, if you havent backed up the original update.rpf enjoy re-installing

lol thanks . 30 mins to install, back up and running....ahhh the joys of having a back up...