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Vertex Normal Editing Bug - Maya 2022 and previous [STILL HAPPENING IN 2025!]

Message 1 of 10
688 Views, 9 Replies

Vertex Normal Editing Bug - Maya 2022 and previous [STILL HAPPENING IN 2025!]

I will start by saying I've encountered this bug in at least the last couple of versions of Maya while creating models for work.


On most of our models we use custom edited vertex normals to achieve specific shading, and not have to use normal maps. I have found that occasionally while editing normals with BOTH of either the 'Vertex Normal Edit Tool' or 'Set Vertex Normal', when I select a vertex or a group of vertices, and then edit their normals using one of those tools, vertex normals OTHER THAN those I have selected suddely shift to all point in a singular random direction. When I hit undo it does not undo this. Although sometimes I will be able to revert the error if I am able to undo enough times, but sometimes that means I lose other edits I have made to the model previous to the action which triggered the bug.

This would lead me to assume it has something to do with those tools interacting with the history stack on a mesh.

However I seem to have some traumatic memory where it has occurred even after I have fully deleted the history on a mesh and frozen transforms.


Any help would be appreciated, as it is very frustrating when you are creating custom vertex normals for a complex object, and you edit one vertex normal and random vertices all over the rest of the model are now screwed up and you can't undo it. You can only go back and re-do all the work you've previously done and hope that the same bug doesn't just occur again.

Unfortunately this is the best information I can provide, as it seems to happen at random while working. So unfortunately no solid repro steps, and no screenshots right now.

I am running Maya 2022.1 at the moment but this has happened to me in 2020, and I'm fairly sure 2019 as well.

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Message 2 of 10
in reply to: paul

I have had this issue occur again and have documented it as best I could. Here are some screenshots showing the correct normals, the random screwed up normals, and the undo history required to reverse the issue.

Screwed up:




Undo history from Script Editor:

Undo History.png

So maybe something to do with Freeze Transformations and custom vertex normals?

Message 3 of 10
in reply to: paul

@sean.heasley g'day mate. sorry to randomly tag, but you've helped out on threads i've been in before, just wondering if this bug could get some visibility/attention. it makes work very frustrating.

Message 4 of 10
in reply to: paul

I've had the bug happen again, and once again when I undo until it goes away it's either Freeze Transformations or Delete History that seems to be the culprit. (Or at least for some reason always what I have to undo up to in order to actually undo the bug)

This time however, i undo-ed until it corrected, and then saved my scene, after which Maya automatically selected a bunch of edge, face, and vertex components on that mesh without me doing anything except hitting ctrl+s.


I have had a hunch for a while (and this reinforces my hunch) that this all somehow has something to do with some kind of hidden pre-selections. Like the component selections of different types that are cached for that mesh are being called up when using the vert normal editing tools, so that when it looks like you have only the intended vertices selected, you then make your edit and it applies an edit to everything including those hidden pre-selections.


Message 5 of 10
in reply to: paul

could you zip and upload this model for us to look at please? Perhaps include the textures as well.

Message 6 of 10
in reply to: paul

Sorry, haven't had a chance to grab that scene file at this stage. Just checking back in to make an extra note, which makes me the think there is a much broader problem involving certain operations and per-mesh stored component selections.


I've just had a similar situation occur, except this time while using "Apply Color" to edit the vertex colours on my mesh.

What is happening is that I am applying some vertex colour while in face selection mode, with certain faces selected, and for some reason when I hit "Apply" it is not only applying the colour to the selected faces, but also applying it to the vertices which are automatically selected for that mesh when I swap back into vertex selection mode.

Seems like a similar issue to me so I thought I'd update this thread with it.

Message 7 of 10
in reply to: paul

To be honest I don't even know if it's the saved component selection that's doing it. It just seems like for some reason there are some vertices that have some kind of quantum connection, where when I affect one's stored vertex data (vert normals, vert colours) it also affects the other (or multiple others).

Seriously so strange.

Message 8 of 10
in reply to: paul

Can confirm this is annoyingly STILL HAPPENING in Maya 2025. Just downloaded it today to try, thinking surely this will have been fixed by now. Nope, didn't even get through one day of working in Maya 2025 before it happened.


Look at what it has done to the vertex normals of my model.



I had selected the vertices I wished to edit the normals of, and as soon as I touched the gizmo, all these random verts had their normals go absolutely haywire.


I can't be the only one who this is happening to.

Message 9 of 10
in reply to: syracoj

Here is a model that I was working on today in Maya 2025 when I ran into this issue yet again.

The object pCube1___BUGGED shows a version after the bug has occurred.
The object pCube1 is in a state where there issue will occur if you select some vertices and then try to edit their vertex normals using the Vertex Normal Edit Tool.

Message 10 of 10
in reply to: paul

thanks for the model and info. I will take a look at this soon.

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