PROBLEM:
As a result of Substance Designer updates, it now writes MDL files in an updated format.

The current MDL format is "1.5" and it fails to load into iClone.


VERY IMPORTANT:
See the last paragraph at the bottom of this report.


REQUEST:
Update iClone's Iray plug-in to support the 1.5 formats of MDL files.
If there is a 1.6 or higher format, support that too.


DETAILS:
1) Substance Designer (SD) v2018.1.2 exports MDL files in 1.3 format, and that works fine in iClone.
2) If you open a v2018.1.2 Substance file in v2019.2.2 of SD, it will export the MDL in 1.4 format, which also works in iClone.
3) If you create a new file MDL file in v2019.2.2 of SD, it will export the MDL in 1.5 format, which FAILS in iClone

The MISLEADING ERROR MESSAGE is shown in the attached picture.


TO DUPLICATE:
1) Open a current version of Substance Designer... v2019.2.2 or higher
1.1) I don't know the exact version where this problem started - v2018.1.2 is fine, but v2019.2.2 has the problem
2) File --> New MDL Material...
2.1) Select the "Physically Based (Metallic/Roughness) Graph Template... Click OK
2.2) There is no need to edit the graph
2.3) You don't even need to save it before proceeding
3) Right-click on the MDL Package --> Export MDL Module...
3.1) Give the MDL a name and save it
4) In iClone, in the Iray plug-in, "Load Custom MDL" and select your new material
4.1) See the error message


IMPORTANT NOTE:
The error message is misleading.
See Picture #1.
The error message implies there is a problem with the Iray MDL Path, but v1.3 and v1.4 format MDL files will load fine, but a v1.5 format MDL file in the same directory will fail.


LASTLY:
I included three sample MDL files.


I THINK I FIGURED OUT WHAT THE PROBLEM IS:
It's the "hair_bsdf" support in the new file format.
In the "1.5" file, if you remove the "hair_bsdf" references AND change the version indicator to "1.4" it will work.
See Picture #2.


P.S.
I don't know what other new features exist in the "1.5" file format which might also need to be supported. You'll need to check the Substance Designer MDL documentation.

P.P.S.
As I thought about this more, I became curious about why iClone even cares about the contents of a "custom MDL" file. iClone does not attempt to render the material. It just passes that data to Iray, right? iClone does not need to "convert" the material in the same way it auto-converts iClone materials to the Iray format. Maybe I'm wrong about that, but it's strange that iClone would be concerned with the actual contents of the "Custom MDL" file at all.