I have one vtu file, it has an “AppendedData” section, in this section, it contains the binary data of all cells. I can open this file without any error in paraview(I know this software also uses vtk), but If I try to read that file by using vtkXMLUnstructuredGridReader directly, it will failed. like this.
and the vtu file I used is here(I zipped the file)
step_t0001.zip (2.3 MB)
Paraview version:5.11.1
Vtk version: 9.2.0-pv5.11.0
OS: Win 11