Hops bug? Could not load file or assembly 'System.Collections.Immutable

Grasshopper Hops
1

Hi :waving_hand:
Hops component returns:
Error building script: Could not load file or assembly ‘System.Collections.Immutable, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’. Could not find or load a specific file. (0x80131621): component “C# Script” (a8987d9a-2383-45bf-ab13-6743248eb333)

If I open the gh file executed in Hops then everything looks fine, no complains from C# component.

The files were created initially in Rhino 8.

Files attached below.

Rhino 9 SR0 2026-6-16 (Rhino WIP, 9.0.26167.11545, Git hash:master @ 57b70c19c1a95d556312e40efd60cd1c4e9f7aaf)
License type: Commercial, build 2026-06-16
License details: Cloud Zoo
Expires on: 2026-07-31

Windows 11 (10.0.26100 SR0.0) or greater (Physical RAM: 32GB)
.NET 10.0.9

Computer platform: DESKTOP

Standard graphics configuration using DirectX
Primary display: AMD Radeon Pro W5700 (AMD) Memory: 8GB, Driver date: 9-25-2025 (M-D-Y). DirectX(11)

Accelerated graphics device with 7 adapter port(s)

  • Secondary monitor attached to adapter port 0
  • Windows Main Display attached to adapter port 1

Secondary graphics devices.
None found.

DirectX Settings
Safe mode: Off

OpenBLAS: OpenBLAS 0.3.30 DYNAMIC_ARCH NO_AFFINITY Zen MAX_THREADS=64.

Rhino plugins that do not ship with Rhino
C:\DEV\Projects\RhinoMCP\rhino\plugin\bin\Debug\net8.0\RhinoMcpPlatform.rhp “RhinoMcpPlatform” 0.2.0.0

  • 3 custom plugins
    Rhino plugins that ship with Rhino
    C:\Program Files\Rhino 9 WIP\Plug-ins\Commands.rhp “Commands” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\rdk.rhp “Renderer Development Kit”
    C:\Program Files\Rhino 9 WIP\Plug-ins\UpdatesAndStatistics\UpdatesAndStatistics.rhp “UpdatesAndStatistics” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\NamedSnapshots.rhp “Snapshots”
    C:\Program Files\Rhino 9 WIP\Plug-ins\MeshCommands.rhp “MeshCommands” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\IronPython\RhinoDLR_Python.rhp “IronPython” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoCycles.rhp “RhinoCycles” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\Grasshopper\GrasshopperPlugin.rhp “Grasshopper” 9.0.26167.11545
    C:\Program Files\Rhino 9 WIP\Plug-ins\Displacement.rhp “Displacement”
    C:\Program Files\Rhino 9 WIP\Plug-ins\SectionTools.rhp “SectionTools”

Margins axis.gh (11.0 KB)

Parent definition.gh (5.3 KB)

2

@AndyPayne , could you take a look?

Probably the hint in NET 8 version used in hops?
\AppData\Roaming\McNeel\Rhinoceros\packages\9.0\Hops\0.17.0\rhino.compute\rhino.compute.runtimeconfig.json:
{

“runtimeOptions”: {

"tfm": "net8.0",

"includedFrameworks": \[

  {

    "name": "Microsoft.NETCore.App",

    "version": "8.0.0"

  },

  {

    "name": "Microsoft.AspNetCore.App",

    "version": "8.0.0"

  }

\],

"configProperties": {

  "System.GC.Server": true,

  "System.Reflection.Metadata.MetadataUpdater.IsSupported": false,

  "System.Runtime.Serialization.EnableUnsafeBinaryFormatterSerialization": false

}

}

}