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Guide export error


i am trying to export my guide and its not working - script editor error

# Warning: pymel.core.general : Could not create desired MFn. Defaulting to MFnDagNode.
# Warning: pymel.core.general : Could not create desired MFn. Defaulting to MFnDagNode.
# Warning: pymel.core.general : Could not create desired MFn. Defaulting to MFnDagNode.
# Error: RuntimeError: file S:/Maya_2023_DI/build/RelWithDebInfo/runTime/Python/Lib/site-packages/maya/OpenMaya.py line 5067: (kInvalidParameter): Object is incompatible with this method

Building from that exact same guide spits out no errors and seems to be working just fine…

Do you have an idea what could be causing this?


anyone has some hint?

That error doesn’t seem to be mGear code related. I would start narrowing the issue.
Did you try restarting Maya? Can you export other guides?
If others work, and this one doesn’t perhaps something in it is broken? I’d start stripping parts out until it can export, assuming it is the only guide file you have that’s broken.

it just happens when exporting this particular guide but i can build the rig from that exact same guide with no issues

So if it’s just this one specific guide, something is off about this particular one. Start stripping parts off, and try exporting each time. Don’t save it, just try to find the problem by process of elimination. Once you can successfully export, re-open the intact file and rebuild only that module part and see if can now export.
Another idea to try is to create a new guide group, and parent your setup under the new guide group, and try exporting that. Your global guide settings will get reset, so keep that in mind.

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Warning: pymel.core.general : Could not create desired MFn. Defaulting to MFnDagNode.

  1. Do you have deltaMush in your scene? I’ve seen that same warning because deltaMush wasn’t implemented properly in the MfnDagNode class. That’s an old problem. But it doesn’t seem related to the error, and you can probably safely ignore it.

Error: RuntimeError: file S:/Maya_2023_DI/build/RelWithDebInfo/runTime/Python/.....OpenMaya.py

  1. For the error, it’s pointing to this path. Do you know what this path is? It is a tool or package you’re using? Or “Deb” is this some Linux package? Or is that some custom path where you saved Maya?

  2. Trying to export your guide how? Maya export? mGear “Export Guide Template”?


its really strange because i dont even habe an “S;” Drive on my sytem!

i dont have delta mush in my scene no

Hi Chris

i found that the issue was in the controlBuffer shapes.

After deleting all the buffered shapes i could export the guide!

Maybe something y can look at for future updates?

You didn’t answer what kind of “export” you are doing.

i always export the guides through Mgear shifter menu/export guide template

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is there a better / safer way to do it?

I’m not saying that. But you didn’t say what command you were trying to run, so we can’t test it and fix it.

Now it’s clear, thanks!

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Hi @actoratwork

I just looked at your guide that you sent me. There is some weird bug in three of your controlBuffer shapes.

import pymel.core as pm

Something is wrong with those geometries. Nothing is visible. And if I try to select the CVs with Python, I get the same weird RelWithDebInfo error.

My conclusion is that those pieces of geometry got corrupted somehow. I can’t possibly guess why or how.

If you delete these 3 controlBuffer nodes, then the guide export stops failing.

You can also replace the shapes with a different icon using mGear’s replaceShape command.

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Thank you Chris,

i had deleted the control verts as those should have no visible controls. Probably i have to do it differently…

Oh yeah, I guess that would do it!

Delete the entire shape node, not the CVs. You’ll be left with an empty transform in your controlBuffers, and that is valid.

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thanks for you had taken the time and check this!

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No problem. Still such a weird misleading error. “RelWithDebInfo”. I think someone left some sloppy code over at Autodesk.

Hey Chris, I’m getting this same guide export error and it looks like it’s probably related to one or some of my control buffer objects. How were you able to determine which controlBuffers were tainted? I have a whole bunch and don’t know how to inspect them all for problems.


To find the problem, I did a lot of tedious trial and error. Deleting half the shapes, and trying to export. Eventually I narrowed it down to which ones were the problems. But I didn’t know WHY.

After actoratwork replied, I realized the shapes had no CVs. And if a nurbs shape has no CVs, then Maya fails to work with it. The correct way to delete it is to delete the entire shape.

Here is a Python script that can find and select the transforms of empty Nurbs shapes that have no CVs. (You might have a different problem. But otherwise, hopefully this can help you.)

import pymel.core as pm

# Find all nurbs curves and surfaces
allNurbs = pm.ls(type=['nurbsCurve', 'nurbsSurface'])

# Try to count the cvs. If it has none, it will fail.
problemNurbs = set()
for each in allNurbs:

# Select the transforms of the ones with no CVs
pm.select([nurb.getTransform() for nurb in problemNurbs])

One you find the problem nurbs, the solution is just to delete their shapes:

# "allNurbs" is finding the nurbs shapes.
# So you can just delete these. It will leave the empty controlBuffer transforms.

Awesome, this worked perfectly. It seems that somehow in the process of extracting custom control shapes, shapes with no verts were created and nested in under the control shape’s transform. I have no idea what I did to mess those up but this makes it an easy mistake to fix at least. Thanks!