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)
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)