Cannot open .xdmf files in legacy version of fenics + latest Paraview

General
2

Please post the contents of the XDMFFile?

Additionally, could you use ascii encoding and add the output of your xdmf file, i.e.

encoding = XDMFFile.Encoding.ASCII
file = XDMFFile("poissonFile.xdmf")
file.write(u,encoding=encoding)