I just upgraded both Houdini (18.5.633) and HtoA (htoa-5.6.3.0_r416179f_houdini-18.5.633.py3) and tried to render an older scene with Arnold. Rendering to disk works fine (even though the installer did set the PATH to "../htoa-5.6.3.0_r416179f_houdini-${HOUDINI_VERSION}.py3./scripts/bin" originally in houdini.env - be aware of the dot '.' behind py3), but if I try to render using the Render View I get:
00:05:19 959MB ERROR | node "driver_houdini" is not installed
Nothing happens after that ...
Any hint what might have gone wrong?
Unfortunately not. I've never been able to figure that one out. I've spent a long time going over Process Monitor logs from Windows machines where that happens. Everything says that the driver_houdini image is loaded, but somehow Arnold cannot load it when you go to render.
Sometimes it goes away after a restart.