Can't assign shaders - error parsing arguement

[arcon76]

Maya 2017 has a bug where sometimes a shader will randomly get corrupted, with any attempt to apply a different shader to the object its on resulting in the following error:

// Warning: line 1: Node 'polySurfaceShape21921.instObjGroups[0]': cannot make assignment to 'rs_woodSG1' shader. // 
// Error: line 1: Error while parsing arguments. // 

The only solution I've found is deleting the shading network & making a new one. Just more 2017 buggy bullcrap.

[BenBisares]

Do you have an archive (File > Archive Scene) of a scene that exhibits this behaviour that you can share with us?

From my experience we have seen this happen with scenes that have nested references and/or multiple render layers.

We have a ticket open with development for what I believe is the same issue but it's still under investigation so we would like as much data as we possible.

[Christoph_Schaedl]

try deleting the history and assign the labert1 shader first...

[arcon76]

Hi sorry for the extreme delay in my reply. The behaviour seemed to correct itself as I progressed the project (I should've saved a version with the fault lol), however I will keep an eye out for it on my next project and report back here if I see it again.

[creationasif]

hey

create a copy of this file 

and unlink your all shader connection by using this script.

global proc unlinkall()
{
string $lsm[] = `ls {"_UNKNOWN_REF_NODE_*"}`;
catchQuiet(`delete $lsm`);

string $objs[] = `ls -type mesh-long -type shape`;
int $i=0;
int $j=0;
int $m=0;
int $k=0;
for($i=0;$i<size($objs);$i++)
{
int $chk=`gmatch $objs[$i] "*Ctrl*"`;
if ($chk==0)
{
string $cons2[]=`listConnections -type "shadingEngine" -p true -s true $objs[$i]`;
for($j=0;$j<size($cons2);$j++)
{
string $cons3[]=`listConnections -p true -s true $cons2[$j]`;
catchQuiet(`disconnectAttr $cons2[$j] $cons3[0]`);
catchQuiet(`disconnectAttr $cons3[0] $cons2[$j] `);
} 
} 
}
}
unlinkall();

After asign lambert1.

and do shader transfer from old file.

problem will solve.. if still there is any issue feel free to ping me 

[resorsky]

This is not solution! The soultion is repair the bug in SG itself. Problem usualy appear when you copy shader with shading group and try assign it to different model. But i never notice this bug when i copy only shader without shading group. The best solution for non destructive way is delete SG and assign again shader to object, then the new SG create automaticly and everything works fine. The bug exist since maya 2012 even earlier I think. It's very anoying, appear not often, but when it appear it could mess all scene file. I dont know why somebody in autodesk dont notice that.

[rockyhCU7BB]

And it's still happening in Maya 2018.. exact same issue, same solution. When I duped a shading network and assigned it to a different object, I got exactly same msg - error parsing argument. So I just had to delete the new SG and assign different texture or rebuild the SG on my own. 

[gferra21]

I found this thread for the "error while parsing arguments" when trying to assign another shader. I'm working in Maya 2020 with render layers, which I hear is sometimes connected to this issue...This bug still exists. Unlinking all of my shaders is a huge hassle, and would rather go back to an old file and lose an hour of work. Really hope this bug gets fixed. 

[tnZADWX]

The bug is still here in 2022.2. I get it all the time - 😩😩😩

[sarawilde7]

Encountered this bug in 2022 with duplicated shader graphs. Huge time waster. Thanks for the thread though glad to see users are at least tracking this. 

[Henrik_Cederblad]

Here's another report of this happening in 2022.3 while assigning an existing ai_StandardSurface material to multiple objects.

[tommie.christiansen]

Have had issues with this since maya 2015. There is some funky stuff going on with how Shadinggroup Sets are connecting to nodes atleast. 

[ktplive]

Had this issue when I was using cmds.createNode('shadingGroup' etc....  to create the shading group

Soon as I changed it to some of my older scripts which used:

cmds.sets(empty=True, renderable=True,noSurfaceShader=True, name=name+'SG');

I could start assigning via cmds.hyperShade(a='Material Name')

[joshoantonio]

This was exactly the issue! Thanks!

[ingemaryinsturain]

I fixed by exporting the object as obj and importing it back into the scene. This is how he dissociates itself from the SG

[severinderek · Accepted solution]

Late reply, but hopefully it will help users encountering the same issue.

We had this issue in Maya 2020, but it does not seem to be related to the version of Maya, as it is still happening in Maya 2022.

Found out that (in my case) the issue was related to the shading group not being connected to a render partition.

Don't know how this happened, but it seems to have been corrupted somewhere.

By adding the connection to the SG, it solves the problem.

In MEL:

connectAttr "<SHADING_GROUP>.pa" ":renderPartition.st" -na;

where "<SHADING_GROUP" is the name/path of the shading group node.

Example:

connectAttr "mainShaderSG.pa" ":renderPartition.st" -na;

Of course, deleting and recreating a new SG also works, but sometimes you don't want to delete the nodes.

[infoLUD4N]

I can't see the reason to keep making new versions of the software when stupid bugs like this won't be fixed. The same with the pivot snap issue that have been there for years. Come on, this is totally basic functions, we are paying money for this to work 😞

[tompainterbigman]

+1 this is a super annoying bug I'm getting it every week at the moment

[tompainterbigman]

todays version of this bug has something to do with namespaces for me, the script editor reads..

sets -e -forceElement A_v22cloth1:blinn3SG;

I can assign other materials just not this one

[matthias.richter]

Life saver!