# Mesh import with binary Gmsh version 4 fails **URL:** \ **Category:** Errors\ **Tags:** mesh\ **Created:** [3 September 2025 10:19 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293 "2025-09-03T10:19:12Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![AlmostSurelyRob](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/almostsurelyrob/32/446_2.png) [@AlmostSurelyRob](https://pyfr.discourse.group/u/AlmostSurelyRob)\ **Post date:** [3 September 2025 10:19 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293/1 "2025-09-03T10:19:12Z")
I have a Gmsh mesh with a header which looks like this ```plaintext $MeshFormat 4.1 1 8 $EndMeshFormat $Nodes ... ``` And it fails to import to PyFR with an error: ```bash Traceback (most recent call last): File "/home/rms/.local/share/uv/tools/pyfr/bin/pyfr", line 10, in sys.exit(main()) ^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/ __main__.py", line 124, in main args.process(args) File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/ __main__.py", line 135, in process_import reader = get_reader_by_extn(extn, args.inmesh, args.progress) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/readers/ __init__.py", line 17, in get_reader_by_extn return reader_map[extn](*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/readers/gmsh.py", line 217, in __init__ for l in filter(lambda l: l != '\n', mshit): ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/progress.py", line 165, in wrap_iterable for i, v in enumerate(iter): ^^^^^^^^^^^^^^^ File "", line 322, in decode UnicodeDecodeError: 'utf-8' codec can't decode byte 0x80 in position 1115: invalid start byte ``` I suspect that PyFR Gmsh import is limited to a version and ASCII/binary representation. Could you please confirm? If yes, could this be explicitly stated in the documentation? Also, note that the link to Gmsh [here](https://pyfr.readthedocs.io/en/latest/user_guide.html) is dead. ---
**Author:** ![AlmostSurelyRob](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/almostsurelyrob/32/446_2.png) [@AlmostSurelyRob](https://pyfr.discourse.group/u/AlmostSurelyRob)\ **Post date:** [3 September 2025 10:46 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293/2 "2025-09-03T10:46:57Z")
[meshio](https://pypi.org/project/meshio/) is useful tool for converting meshes between formats: ```bash meshio convert \ --ascii \ --input-format gmsh \ --output-format gmsh22 \ mesh_gmsh4.msh mesh_gmsh22.msh ``` Now trying with it though encountering a different problem: ```plaintext Traceback (most recent call last): File "/home/rms/.local/share/uv/tools/pyfr/bin/pyfr", line 10, in sys.exit(main()) ^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/ __main__.py", line 124, in main args.process(args) File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/ __main__.py", line 138, in process_import mesh = reader.to_pyfrm(args.lintol) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/readers/base.py", line 22, in to_pyfrm mesh = self._to_raw_pyfrm(lintol) ^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/rms/.local/share/uv/tools/pyfr/lib64/python3.12/site-packages/pyfr/readers/gmsh.py", line 420, in _to_raw_pyfrm pents = self._felespent, self._bfacespents, self._pfacespents ^^^^^^^^^^^^^^^ AttributeError: 'GmshReader' object has no attribute '_felespent' ``` ---
**Author:** ![fdw](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@fdw](https://pyfr.discourse.group/u/fdw)\ **Post date:** [3 September 2025 11:37 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293/3 "2025-09-03T11:37:52Z")
Please see: > which should clarify what’s supported and how the mesh needs to be prepared. Regards, Freddie. ---
**Author:** ![AlmostSurelyRob](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/almostsurelyrob/32/446_2.png) [@AlmostSurelyRob](https://pyfr.discourse.group/u/AlmostSurelyRob)\ **Post date:** [5 September 2025 14:47 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293/4 "2025-09-05T14:47:04Z")
Thanks. This is clear and precisely what I needed to know. The mesh was missing PhysicalName section and the fluid tag. I’d like to ask a follow-up question though. The version 2.8 has no backward compatibility with 2.2 offered by meshio, is that right? Just for background, I am sorry, I am in a little awkward situation as I don’t have the mesh. I am helping with a conversion. I wrote a little script which reapplies the tags but I couldn’t yet get it to work with 4 yet so exported to gmsh22. PyFR now complains about unpaired faces, which I suspect is due to either missing data in the mesh I was given, something amiss with my conversion script or gmsh22 not being supported in PyFR. I just want to eliminate the last option. ---
**Author:** ![fdw](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@fdw](https://pyfr.discourse.group/u/fdw)\ **Post date:** [5 September 2025 15:01 UTC](https://pyfr.discourse.group/t/mesh-import-with-binary-gmsh-version-4-fails/1293/5 "2025-09-05T15:01:21Z")
I think 2.8 is a typo in the docs. The version the code supports is 2.2. I’ll get that fixed. Regards, Freddie.