I found the solution to this problem, but not why the problem occured. My guess would be that episerver cached the renderer and try to access an older version of it that did not exist.
Solution was that the renderer for the block seemed to be corrupt in some way. What I did was to delete the webcontrol that was the renderer, enter edit mode and get the error "no renderer was found for block and then create it again.
So the problem the problem seems not to have been with the xforms module.