Simul8 — Known Issues & Workarounds¶

This page documents recurring installation and runtime problems with Simul8, their causes, and confirmed workarounds. For installation procedures, see Setup & Installation.

Maya License Corruption / License Expired After Logout¶

Symptom: After restarting Maya, restarting the computer, or signing in/out of an Autodesk account on a different machine, Simul8 displays:

License file is Expired
License File is corrupt

Affected versions: Primarily v1.x

Cause: The license text files become corrupted or invalidated when the Autodesk account state changes, or when Maya's internal license session changes. The root cause has not been fully pinned down by MRMC.

Workaround (confirmed by @jtread):

Locate the two Simul8 license text files in your Simul8 scripts or core folder.
Rename them to a different name (e.g. add _backup to the filename) and move them to a separate folder.
Rename them back to their original correct names.
Place them back in the original folder.
Relaunch Maya — Simul8 should now recognise the license again.

This workaround has been confirmed to work across multiple license files received over time.

Use the correct version for your Maya

Using the new Simul8 version with the correct license (issued by Gordon at MRMC) and with a default C: installation path also prevents many license issues. Do not install to a non-standard path.

WMIC.exe Missing on Windows 11 — License Registration Fails¶

Symptom: When clicking the Info icon on the Simul8 shelf to register a license, you see:

Command 'wmic csproduct get UUID' returned non-zero exit status 1

The license registration window cannot retrieve the machine UUID and the license cannot be activated.

Affected versions: v2.1.1 and later; Windows 11 (recent builds)

Cause: Microsoft removed WMIC.exe from Windows 11 as a default component in recent feature updates.

Fix:

Open Windows Settings.
Go to System > Optional features (or search "Optional features").
Click Add an optional feature.
Search for WMIC.
Install it.
Restart Maya and click the Info icon again — the UUID should now be retrieved correctly.

PyMel Not Installed — Maya Won't Start Simul8 (v2.0.0+)¶

Symptom: After installing Simul8 v2.0.0 or later and enabling it in Maya's Plugin Manager, Simul8 fails to load, or Maya crashes/freezes on launch.

Affected versions: v2.0.0+ on Maya 2023 and later

Cause: From Maya 2023, Autodesk removed PyMel from the Maya distribution. Simul8 requires PyMel and attempts to install it automatically on first load.

Fix — Option A (auto-install):

Run Maya as Administrator for the first launch after installing Simul8.
Enable Simul8 in the Plugin Manager.
Simul8 will detect that PyMel is missing and install it automatically (approximately 30 seconds).
The .whl file is included in:
v2.0.0: plug-ins/Simul8/PyMel/ folder
v3.x: third_party/ folder

Fix — Option B (manual pip install):

cd "C:\Program Files\Autodesk\Maya2025\bin"
mayapy -m pip install pymel

Adjust the path for your Maya version. The specific version required is:

Simul8 v2.0.0: PyMel 1.4.0
Simul8 v3.x: PyMel 1.5.0 (community confirmed)

CSV Header Row Count Mismatch on Filtered Move Import¶

Symptom: When importing a filtered or modified Simul8 move into Flair, the import dialog shows a frame count mismatch error related to the CSV header rows.

Affected versions: v2.1.0

Workaround: In the import dialog, change the displayed value to the expected written value minus the number of header rows. The header rows are counted as data rows in some import paths.

Status: This issue was fixed in v2.1.0. If you encounter it, verify you are on the latest Simul8 version.

Plug-in Installs to Wrong Maya Folder¶

Symptom: After installing Simul8 on Maya 2019 or 2020, the Simul8 shelf does not appear, or the plug-in will not load.

Affected versions: v1.x

Cause: The installer defaults to the Maya 2018 plug-ins folder even if Maya 2019 or 2020 is installed.

Fix:

Navigate to C:\Users\[User]\Documents\maya\2018\plug-ins\ (or equivalent).
Move (do not copy) the Simul8 folder to the correct Maya version folder: C:\Users\[User]\Documents\maya\2020\plug-ins\.
Also check that Simul8.mod is in the corresponding modules folder.

Non-English Windows — `No module named checkPymel` Error¶

Symptom: Simul8 will not load on a Windows system with a non-English display language (e.g. Slovak, German). Error:

No module named checkPymel

Cause: Windows localises folder names in C:\Users\... based on the display language. The compiled .pyc modules contain hardcoded paths that expect English folder names.

Fix: Change Windows display language to English. Restart Maya.

v3.0.0 Exports Fail on Maya 2025¶

Symptom: Simul8 v3.0.0 is installed on Maya 2025 but carts or axis exports fail or produce invalid files.

Cause: Simul8 v3.0.0 was compiled for Maya 2026. It is not compatible with Maya 2025.

Fix: Use Maya 2026 with Simul8 v3.0.0 or later. For Maya 2025, use Simul8 v2.1.1.

Wrong Carts Export Values (Aux Nodes + Keyed-Only Unchecked)¶

Symptom: Carts export produces incorrect values when aux nodes are selected and "keyed-only" is unchecked.

Affected versions: v3.0.0

Status: Fixed in v3.1.0. Update to v3.1.0 or later.

Issue Summary Table¶

Issue	Versions Affected	Workaround
License shows "expired" or "corrupt"	v1.x	Rename license files to new name and back
`wmic csproduct get UUID` error on license registration	v2.1.1+ / Windows 11	Install WMIC via Optional Features
PyMel missing — Maya won't start Simul8	v2.0.0+ / Maya 2023+	Run Maya as admin first time; or manual pip install
CSV header row import error	v2.1.0	Subtract header row count from import value
Plug-in installs to Maya 2018 folder	v1.x	Move Simul8 folder to correct Maya version folder
Non-English Windows — `No module named checkPymel`	v1.x	Change Windows language to English
Exports fail on Maya 2025	v3.0.0	Use Maya 2026 for v3.0.0+; use v2.1.1 for Maya 2025
Wrong carts export with aux nodes + keyed-only off	v3.0.0	Fixed in v3.1.0

Source: Simul8 Maya License Corruption — talk.mrmoco.com
Source: AUDIT_SIMUL8.md — Known Issues section compiled from 12+ forum topics