"Assembly resolver failed to load assembly"

Currently running RiR (Revit 2023.1) with R8. When I open Grasshopper, I get a string of messages saying “Assembly resolver failed to load assembly” for various assemblies including core GH assemblies as well as for plugins. However, everything still seems to work fine. Just curious if anyone else experienced this? Is this going to be a problem or can I safely ignore?


Note that there is a See Details option to get more info in the dialog.

Lets first start by updating to the Latest Rhino and Rhino.Inside.Revit

https://www.rhino3d.com/inside/revit/1.0/

Then lets troubleshoot Revit Plugins and if need be Rhino/GH plugins.

Hi Japhy,

Thanks for the quick response - I’ll definitely give that a try and get back to the forum.

One quick question - should the plugins in …\AppData\Roaming\Grasshopper\Libraries also be cleared out?

It seems that this folder is shared regardless of whether Grasshopper is run on R7 vs R8? How should we look to isolate certain plugins in this folder depending on the Rhino/.NET version that is run? Can they be appropriately moved to the …\AppData\Roaming\McNeel\Rhinoceros\packages folders?

That is typically handled by the installer, are you installing via package manager?

Generally yes, unless it isn’t available in the package manager.

If you aren’t installing via package manager you could manually separate by the same process.

C:\Users\yourUserNameHere\AppData\Roaming\McNeel\Rhinoceros\packages

in this folder you will see subfolders for 7.0 & 8.0.

To add a Rhino 8 only GH plugin, in this example Sunglasses. I created a Sunglasses folder in the 8.0 directory, added a manifest.txt with the folder name 8_only (name this whatever you want), which houses the .gha file.

I upgraded both Rhino and Rhino.Inside.Revit but I’m having the same issues.

  1. When I run without other Addins, it runs without the “Assembly resolver failed to load assembly” warnings.

  2. When I remove all Grasshopper plugins and run it, I get the warnings again.

Note that I have all plugins removed from the folders below, but it still manages to somehow find some plugins (such as karamba and kangaroo2) when loading. However, I don’t think this is the issue because it loads those same plugins when I “Run Revit without other Addins…” option.


Is there anything else I can try?

By the way - no such issues with Revit 2025 and Rhino.Inside.Revit. It must be an issue with .NETFramework vs .NETCore…

But again, there is no visible issue with this - everything still works fine; I was just curious what it was.

Thanks for your help Japhy, let’s consider this closed…

That is a big clue. Revit 2025 runs in .netcore 8, all previous versions are in .Netframework. There must be Rhino/GH plugins specifically targeting .netcore which can’t load in the older Revit environment.