After installing Houdini 16.5 , maya 2016 mental ray plugin is not working
error - “specified procedure could not be found”

Good! That'll show 'em!

Rajesh Mohanty
After installing Houdini 16.5 , maya 2016 mental ray plugin is not working
error - “specified procedure could not be found”

same issue。。。。

Sounds like a library naming conflict with libray. If you turn off autoload on houdiniEngine does mentalRay work again?

If it is a library conflict, the easiest way to deal with it is to run houdiniEngine out of process. While the plugin is still loaded, go into the houdiniEngine Preferences, change the Back End prefs to Named Pipe, and Auto-Start server, save the prefs, and then restart Maya.

Having a similar issue here as well. Only machine I have with Houdini installed is giving the same problem. On that machine Mental Ray has stopped working in Maya 2017 and Maya 2018 and is giving the same error. All other systems without Houdini installed, Mental Ray in Maya works as expected. Mental Ray was working in Maya months ago.

Setting Houdini Back End prefs as explained above does not work.

Unloading the Houdini Engine inside Maya 2018 does not work either.

However, completely uninstalling Houdini from this system permits Mental Ray for Maya 2018 to load again in Maya 2018.

Joey Ponthieux

I can provide further detail.

Working under the presumption that Houdini Engine for Maya was doing something to impair Mental Ray, I reinstalled Houdini on this system but without the Houdini Engine for Maya option selected. Mental then stopped working.

Upon completely uninstalling Houdini a second time, Mental Ray for Maya 2018 returned to working normally.

Joey

There has to be a way to have both co-exist in a system. My work around for the time being is keeping both in separate machines, but that's tactical solution, I hope and not a strategic.

When I try to load the MentalRay plugin with Houdini installed, this message appears:
// Error: file: CProgram Files/Autodesk/Maya2018/scripts/others/pluginWin.mel line 290: The specified procedure could not be found.
(Mayatomr)

I found out that the problem is a DLL File with the SAME NAME in Houdini and MentalRay.

libRAY.dll (C:\Program Files\Side Effects Software\Houdini 17.0.352\bin\libRAY.dll)
libray.dll (C:\Program Files\NVIDIA Corporation\mentalray 3.14 for Maya 2018\bin\libray.dll)

When I rename the DLL in the Houdini Folder, MentalRay works perfectly, but Houdini doesn't anymore.
When I leave the DLL in Houdini, Houdini is working good, but Maya cannot load the MentalRay Plugin.

The issue is having the same name DLL file on my Windows system. No other issue is present except this DLL issue. If there is a way to point to the MAYA dll when loading MentalRay, then it might work. Seems like when Maya is loading the DLL, it is trying to load the DLL from Houdini. Strange. Somone must come up with a solution…

This is the reason big studios have elaborate pipelines so that each package and its dependencies run it their own subshell and are conflict free. Of course, this does not help you, but it's long been an issue. One thing that drove us nuts in the early days of CG pipelines was the LD_LIBRARY_PATH for each package being different and stomping all over each other.

In the short term, just renaming the houdini install folder or the maya install folder when you are using one or the other will take it out of the path (as the path to the files will no longer exist) and hopefully work. This would mean that you can't run them both at the same time though.