It seems Mantra supports automatically generated Normals but alsways uses the default 60 degree cusp angle defined in the Geometry tab of the display options.
Is there a separate parameter to set the automatic cusp angle for Mantra?

Hi. You can add “add normals to geometry” and “cusp angle for vertex normals” from mantra ROP's “edit parameter interface” (or, if you don't want to override it globally, you can add them to individual objects).

I see.
So when it says in the Docs: “The viewport and mantra now support automatically cusped vertex normals.” that means Mantra supports it but does not provide the appropriate parameters by default? Any specific reason for that?

Also why does Mantra render cusped edges with the default cusp angle of 60° then if I do not add the cusp angle and the “Add normals” to the ROP node? shouldn't it render completely smoothed objects?

I am asking to find out if it is connected to the Viewport cusp angle in any way or if it creates its own normals.
Thanks

Cool, I did what you said and it worked the first time but now my mantra node is broken.
Every time I try to create a mantra node now I get that error and the interface is missing most of its parameters.
I didn't even save the changes in the parameter interface.
Also I noticed that when I add the cusp angle paramter first the add vertex parameter gets greyed out and cannot be added to the panel anymore.
Why do you not just add that by default?

The curp angle on display option is not tied to mantra's.

Regarding the error… I'm not sure - I can not reproduce the problem on my end. If error persists across sessions, I recommend wiping away houdini's preference folder and see if the problem goes away. If not, please file a bug with steps to reproduce the problem. Thanks.