VS2026 + .NET 10 broke SvcUtil System.ObjectModel / ObservableCollection

I've been using SvcUtil for a period of 2-3 years to generate the WCF Soap client, but after upgrading the project to .NET 10 things have changed / broken...

**System.ObjectModel**
Visual Studio 2026 reports that the reference to System.ObjectModel should be removed or that it CAN be removed... i'm not sure what the right decision is here.

When using SVCUtil i get this error:

**error:**

> Error: No type could be loaded for the value 'System.Collections.ObjectModel.ObservableCollection`1' passed to the --collectionType option. Ensure that the assembly this type belongs to is specified via the --reference option.
>
> If you would like more help, type "dotnet-svcutil -h"

If i instead use Visual Studio to generate the client, it seems to work, although way slower than SVCUtil... and the following config is generated in my new client:

**Configuration:**
```
{
"ExtendedData": {
"inputs": [
"https://urlurlurlurl/Service_Development.svc"
],
"collectionTypes": [
"System.Collections.Generic.Dictionary`2",
"System.Collections.ObjectModel.ObservableCollection`1"
],
"enableDataBinding": true,
"namespaceMappings": [
"*, ClientCore.ServiceAPI"
],
"references": [
".............SharedCore.dll"
],
"sync": true,
"targetFramework": "net10.0-windows7.0",
"typeReuseMode": "Specified"
}
}
```

So what gives - is SvcUtil supposed to work ? do i need to update something ?

What should i do with System.ObjectModel ?

I guess i'll continue using VS2026 to generate the client for now. it seems to work...

**EDIT:**

I tried removing System.ObjectModel nuget ref.. and VS2026 is able to create the client.