Error "cannot create geometry from incomplete mesh"

Hello,

I am using the fsi module with a 2d geometry, its a circle in a laminar flow.
Everything goes fine for the first 0.5s oft the simulation, but after the 45th automatic remeshing the error "cannot create geometry from incomplete mesh" appears.

Does anyone know how to handle this error, or can anyone tell me what it means exactly?

Thank You in Advance,
Tim.