.NET 10 - System.ExecutionEngineException in System.Reflection.MethodBaseInvoker.InvokeWithOneArg

[vaLP2eh]

Description

I have generic classes/interface with 9 (or more) generic type parameters.

When the type is activated, the runtime crashes with a System.ExecutionEngineException.
There is not much information provided by the debugger: "Exception of type 'System.ExecutionEngineException' was thrown."

Everything works fine on .net 10 when having 8 or less parameters.
Everything works fine in earlier .net versions, even with 9 or more parameters.

Reproduction Steps

void Test()
{
    var i = new MyEntity<string, string, string, string, string, string, string, string, string>(); // <-- Throws System.ExecutionEngineException in System.Reflection.MethodBaseInvoker.InvokeWithOneArg(...)
}

public sealed class MyEntity<TItem1, TItem2, TItem3, TItem4, TItem5, TItem6, TItem7, TItem8, TItem9> : IEditableEntity<TItem1, TItem2, TItem3, TItem4, TItem5, TItem6, TItem7, TItem8, TItem9>
{
    public TItem1 Item1 {get; set;}
    public TItem2 Item2 {get; set;}
    public TItem3 Item3 {get; set;}
    public TItem4 Item4 {get; set;}
    public TItem5 Item5 {get; set;}
    public TItem6 Item6 {get; set;}
    public TItem7 Item7 {get; set;}
    public TItem8 Item8 {get; set;}
    public TItem9 Item9 {get; set;}
}

public interface IReadonlyEntity<TItem1, TItem2, TItem3, TItem4, TItem5, TItem6, TItem7, TItem8, TItem9>
{
    TItem1 Item1 {get;}
    TItem2 Item2 {get;}
    TItem3 Item3 {get;}
    TItem4 Item4 {get;}
    TItem5 Item5 {get;}
    TItem6 Item6 {get;}
    TItem7 Item7 {get;}
    TItem8 Item8 {get;}
    TItem9 Item9 {get;}
}

public interface IEditableEntity<TItem1, TItem2, TItem3, TItem4, TItem5, TItem6, TItem7, TItem8, TItem9> : IReadonlyEntity<TItem1, TItem2, TItem3, TItem4, TItem5, TItem6, TItem7, TItem8, TItem9>
{
    new TItem1 Item1 {get;set;}
    new TItem2 Item2 {get;set;}
    new TItem3 Item3 {get;set;}
    new TItem4 Item4 {get;set;}
    new TItem5 Item5 {get;set;}
    new TItem6 Item6 {get;set;}
    new TItem7 Item7 {get;set;}
    new TItem8 Item8 {get;set;}
    new TItem9 Item9 {get;set;}
}

Expected behavior

An instance of the type should be created without error.

Actual behavior

• Runtime crashes
• System.ExecutionEngineException.
• "Exception of type 'System.ExecutionEngineException' was thrown."

Regression?

Code works fine with

• .net Framework 4.6.2 to 4.8
• .net 3.1 to .net 9.0

Bug appeared with .net 10.

• Reproduced with 10.0.102 (and earlier)

Known Workarounds

No workaround found.

Configuration

• .net 10.0.102
• Windows 11, 25H2, 26200.7623
• x64
• Visual Studio 2026, v18.2.0

Other information

The error was found in unit test (MSTest).

[jkotas]

This works in 10.0.1 and fails in 10.0.2. Likely a regression from #120712

cc @davidwrighton