First run of the "demo" case with openFoam 2.4 yields the following error:
ERROR: In /home/openfoam/OpenFOAM/ParaView-4.1.0/VTK/IO/Geometry/vtkOpenFOAMReader.cxx, line 6467
vtkOpenFOAMReaderPrivate (0x25d7950): Error reading line 21 of /home/alex/DroneCFDSimulation/aoa_0.0/0/omega: Expected number, string or (, found turbulentOmega
I ran with a freshly installed iopenFoam 2.31 as well, and still got the same error.
This is an ongoing issue that I haven't tracked down yet. The simulation data is still there, and you can still access it despite this error message.