ModuleNotFoundError: No module named 'pkg_resources' after loading scitools and um_tools

[Alice Miller (alice-miller)]

When loading a specific version of scitools followed by um_tools, when attempting to run Mule I get the following error:

module purge *
module load scitools/default-2026_06_10
module load um_tools
mule-cumf --help

returns the error message:

Traceback (most recent call last):
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/mule/packing.py", line 46, in <module>
    import um_packing
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/um_packing/__init__.py", line 21, in <module>
    from .um_packing import wgdos_pack, wgdos_unpack, get_shumlib_version
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/um_packing/um_packing.py", line 9, in <module>
    __bootstrap__()
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/um_packing/um_packing.py", line 3, in __bootstrap__
    import sys, pkg_resources, importlib.util
ModuleNotFoundError: No module named 'pkg_resources'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/bin/mule-cumf", line 33, in <module>
    sys.exit(load_entry_point('um-utils==2025.10.1', 'console_scripts', 'mule-cumf')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/bin/mule-cumf", line 25, in importlib_load_entry_point
    return next(matches).load()
           ^^^^^^^^^^^^^^^^^^^^
  File "/data/apps/sss/environments/default-2026_06_10/lib/python3.12/importlib/metadata/__init__.py", line 205, in load
    module = import_module(match.group('module'))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/apps/sss/environments/default-2026_06_10/lib/python3.12/importlib/__init__.py", line 90, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 999, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/um_utils/cumf.py", line 88, in <module>
    import mule
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/mule/__init__.py", line 1788, in <module>
    from mule.ff import FieldsFile  # noqa: E402
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/mule/ff.py", line 29, in <module>
    from mule.packing import wgdos_pack_field, wgdos_unpack_field
  File "/home/users/umadmin/mule/mule-2025.10.1/python-3.9.25_numpy-1.23.5/openmp/lib/mule/packing.py", line 107, in <module>
    raise ImportError(err.args + (msg,))
ImportError: ("No module named 'pkg_resources'", 'SHUMlib Packing library found, but failed to import')

Not specifying a scitools version (i.e. running module load scitools) does not cause any issues. It seems that for some reason specifying the scitools version causes module load um_tools to use Python 3.9 rather than Python 3.12.

Removing the scitools version or specifying the correct um_tools python path manually solves the problem:

export MULE_ROOT=/home/users/umadmin/mule/mule-2025.10.1/python-3.12.13_numpy-2.3.5/openmp
export PATH=$MULE_ROOT/bin:$PATH
export PYTHONPATH=$MULE_ROOT/lib:$PYTHONPATH

The problem occurs on the VDI and on SPICE (not tested on the HPC). Is this expected behaviour?

[Alice Miller (alice-miller)]

It may be worth noting that

module load scitools/production-os48-1
module load um_tools/2026.09.1/openmp

works as expected.

[James Bruten (james-bruten-mo)]

Hi Alice, this is because we haven't previously setup the um_tools modules with the dated default scitools modules, which means the um_tools module falls back to the system python install. I guess this is mainly because no one has asked for it before! I've just updated the 2026.10.1 release with the scitools/default-2026_06_10 module, so

module load scitools/default-2026_06_10
module load um_tools/2026.10.1/openmp

should now work on spice/exab/excd