# Persalys 19.1 - bug while testing a FMU

**URL:** <https://persalys.discourse.group/t/persalys-19-1-bug-while-testing-a-fmu/175>\
**Category:** Persalys usage\
**Created:** [December 12, 2025, 12:48pm UTC](https://persalys.discourse.group/t/persalys-19-1-bug-while-testing-a-fmu/175 "2025-12-12T12:48:08Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![gblondet](https://avatars.discourse-cdn.com/v4/letter/g/d6d6ee/32.png) [@gblondet](https://persalys.discourse.group/u/gblondet)\
**Post date:** [December 12, 2025, 12:48pm UTC](https://persalys.discourse.group/t/persalys-19-1-bug-while-testing-a-fmu/175/1 "2025-12-12T12:48:08Z")

</div>

Hello,

I imported a FMU file into Persalys 19.1 (appimage, on Ubuntu 24 LTS), and I got the following error.

I have checked the documentation : [Installation — Persalys 19.1 documentation](https://persalys.github.io/persalys/latest/installation.html#linux)

```bash
LOG_STDOUT | info | iteration to converge on Fview: 8
Could not find cannot import name 'dopri5' from 'assimulo.lib' (/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/assimulo/lib/ __init__.py)
Could not find cannot import name 'rodas' from 'assimulo.lib' (/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/assimulo/lib/ __init__.py)
Could not find cannot import name 'odassl' from 'assimulo.lib' (/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/assimulo/lib/ __init__.py)
Could not find ODEPACK functions.
Could not find RADAR5
Could not find GLIMDA.
LOG_STDOUT | info | iteration to converge on Fview: 8
Traceback (most recent call last):
  File "<string>", line 11, in _exec
  File "/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/otfmi/otfmi.py", line 480, in __call__
    return self._exec(X, **kwargs)
           ~~~~~~~~~~ ^^^^^^^^^^^^^
  File "/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/otfmi/otfmi.py", line 493, in _exec
    return self.base.simulate(value_input=value_input, **kwargs)
           ~~~~~~~~~~~~~~~~~~ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/otfmi/otfmi.py", line 302, in simulate
    simulation = fmi.simulate(
        self._model,
    ...<3 lines>...
        **kwargs_simulate
    )
  File "/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/otfmi/fmi.py", line 82, in simulate
    return model.simulate(**kwargs)
           ~~~~~~~~~~~~~~ ^^^^^^^^^^
  File "src/pyfmi/fmi2.pyx", line 4808, in pyfmi.fmi2.FMUModelME2.simulate
  File "src/pyfmi/fmi_base.pyx", line 214, in pyfmi.fmi_base.ModelBase._exec_simulate_algorithm
  File "/tmp/.mount_persalCOw5vm/usr/lib/python3.13/site-packages/pyfmi/fmi_algorithm_drivers.py", line 672, in solve
    self.simulator.simulate(self.final_time, self.ncp)
    ~~~~~~~~~~~~~~~~~~~~~~~ ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "assimulo/ode.pyx", line 192, in assimulo.ode.ODE.simulate
  File "assimulo/ode.pyx", line 312, in assimulo.ode.ODE.simulate
  File "assimulo/explicit_ode.pyx", line 137, in assimulo.explicit_ode.Explicit_ODE._simulate
  File "assimulo/explicit_ode.pyx", line 222, in assimulo.explicit_ode.Explicit_ODE._simulate
  File "assimulo/solvers/sundials.pyx", line 2112, in assimulo.solvers.sundials.CVode.integrate
  File "assimulo/solvers/sundials.pyx", line 2130, in assimulo.solvers.sundials.CVode.integrate
  File "assimulo/solvers/sundials.pyx", line 2437, in assimulo.solvers.sundials.CVode.initialize_options
assimulo.exception.AssimuloException: No support for SuperLU was detected, please verify that SuperLU and SUNDIALS has been installed correctly.

```

My FMU was build in Model Echange mode, and depends on the solver provided by Persalys.

However, no problem with FMU exported in “Co-simulation” mode, with embedded solver inside the FMU itself.

Is there any special requirements for Persalys to run FMU in “Model Exchange” mode ?

---

<div class="post-metadata">

**Author:** ![jschueller](https://yyz2.discourse-cdn.com/free1/user_avatar/persalys.discourse.group/jschueller/32/6_2.png) [@jschueller](https://persalys.discourse.group/u/jschueller)\
**Post date:** [January 9, 2026, 2:07pm UTC](https://persalys.discourse.group/t/persalys-19-1-bug-while-testing-a-fmu/175/2 "2026-01-09T14:07:57Z")

</div>

hi, we enabled the superlu solver for the next version

turns out pyfmi switches to a sparse solver when \>=100 variables

> <https://github.com/modelon-community/PyFMI/blob/4b01e08eedd8c54e97b38156cb3ab19c9a149834/src/pyfmi/fmi_algorithm_drivers.py#L556>