UPDATE: Device manager said my drivers were up to date, but I went into the GeForce Experience app and changed from the "Game ready" to the "Studio" driver and that seemed to do the trick. No more error message about Vulkan, either.

Hello,

I installed Houdini 20.5 today to try out the new copnet features, but started getting weird results that do not match what I've seen online. Specifically, the viewport display for SDFshape and the Worley "center" output look different from the tutorial I was following (and from the little preview in the network view), and the Preview Material node is just a blank white square (screenshots attached).

Upon opening Houdini, I was presented with the following error: "Vulkan could not be initialized. Falling back to OpenGL." This is my first time seeing this, having been working in Houdini 20 for the past few months. Might that be related to the viewport issue I seem to be having? I searched the forums and google for this error but didn't find much information.

Did you ever find a solution to that error message?

Glad you found the solution. In general, the studio drivers should be preferred over game-ready -- they're much more stable. The game ready drivers change constantly for big game releases, adding optimizations and bug fixes (they shouldn't have to, but I'm not going to get into that). This seems to cause more frequent regressions with the game-ready driver.