Unable to load plugin, ID already in use


We have a plugin deployed via Yak which installs via the Package Manager (TestPackageManager command on Rhino 6).

I deployed a new version this week and then we found that the plugin cannot be loaded due to “ID already in use”. Now, we have been using the same ID for months now. And this happens on multiple machines (so it is not just a bad setup on one machine).
Removing the plugin physically does not solve the problem.
Reverting to older plugin versions also gets the same error.

Anyone that has seen the same thing?


If you have both a DLL and an RHP with the same name in your package you should delete the DLL.

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I removed the .dll and now it works! Thanks!

@nathanletwory I am developing a regular .rhp that I am installing via .rhi. No .dll, only the .rhp is being used to launch the .rhi. I have the same “Unable to load plugin:ID already in use.” This only occurs when debugging, if opening Rhino normally everything works as expected.

Developing other plugins that work just fine under normal and debug mode, it’s just something with this particular solution is wrong.

Any obvious things I should check for?

Thanks in advance,

Sounds like in your debugging scenario you have the plug-in loaded from two different locations. Uninstall the one installed with the RHI before debugging. And vice versa, when testing your RHI make sure your debug version can’t be found.

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@nathanletwory conceptually that makes sense to me. Can’t get it to work tho. If I delete the .rhi version (which lives under C:\Users\user.name\AppData\Roaming\McNeel\Rhinoceros\6.0\Plug-ins normally) and then launch ‘StartDebug’ from VS, the plugin isn’t loaded…

Weird bc with other plugins I there’s no conflict of versions… The application VS is looking to open during debugging is C:\Program Files\Rhino 6\System\Rhino.exe of course, but how do I know which .rhp VS is using during debugging?

@nathanletwory for now re-pointing my working directory under debugging settings is doing the trick. Thanks!!