Error at start up of omnisharp: mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded

System: ubuntu 20.04

1. Open Visual Studio Code v1.52.1
2. Open my (very big) C# project

Omnisharp mentions me the following errors

Actually, one project of my solution uses these assemblies (microsoft.codeanalysis.*****). But, something interesting: if I put appart the project that references assemblies that seem to be the source of the problem and open it alone in VSCode, I don’t get the problem.

Information: my solution is VERY big.

Starting OmniSharp server at 1/5/2021, 11:31:21 AM
    Target: /home/stephane/Documents/Sources/PMS/src/FundProcess.Pms.sln

OmniSharp server started.
    Path: /home/stephane/.vscode/extensions/ms-dotnettools.csharp-1.23.8/.omnisharp/1.37.5/run
    PID: 9520

Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.csharp.features/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.CSharp.Features.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.
Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.csharp.workspaces/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.CSharp.Workspaces.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.
Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.features/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.Features.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.
Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.csharp.features/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.CSharp.Features.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.
Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.csharp.workspaces/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.CSharp.Workspaces.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.
Can't find custom attr constructor image: /home/stephane/.nuget/packages/microsoft.codeanalysis.features/3.8.0/lib/netcoreapp3.1/Microsoft.CodeAnalysis.Features.dll mtoken: 0x0a000006 due to: Cannot resolve dependency to assembly because it has not been preloaded. When using the ReflectionOnly APIs, dependent assemblies must be pre-loaded or loaded on demand through the ReflectionOnlyAssemblyResolve event.

[AaronJac]

Setting omnisharp.enableMsBuildLoadProjectsOnDemand to true solved the problem for me.

[TheBoneJarmer]

I’m having the same issue. Omnisharp stops functioning more often. I noticed I am spending lots of time trying to get intellisense up and running again. Restarting omnisharp sometimes helps but not always.