`Exception.ToString` is different with .NET 11

[richlander]

Program.cs:

using System;
using System.Diagnostics;
using System.Threading.Tasks;
using System.Runtime.InteropServices;

Console.WriteLine(RuntimeInformation.FrameworkDescription);



await OuterAsync();

static async Task OuterAsync()
{
    await Task.CompletedTask;
    await MiddleAsync();
}

static async Task MiddleAsync()
{
    await Task.CompletedTask;
    await InnerAsync();
   throw new InvalidOperationException("boom");
}

static async Task InnerAsync()
{
    await Task.CompletedTask;
}

project:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>net11.0;net10.0</TargetFrameworks>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <Features Condition="'$(TargetFramework)' == 'net11.0'">runtime-async=on</Features>
  </PropertyGroup>
</Project>

.NET 10 (everything default):

$ dotnet run -f net10.0
.NET 10.0.8
Unhandled exception. System.InvalidOperationException: boom
   at Program.<<Main>$>g__MiddleAsync|0_1() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 24
   at Program.<<Main>$>g__OuterAsync|0_0() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 15
   at Program.<Main>$(String[] args) in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 10
   at Program.<Main>(String[] args)

.NET 11 (async v2 off):

dotnet run -f net11.0
.NET 11.0.0-preview.4.26230.115
Unhandled exception. System.InvalidOperationException: boom
   at Program.<<Main>$>g__MiddleAsync|0_1() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 24
   at Program.<<Main>$>g__OuterAsync|0_0() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 15
   at Program.<Main>$(String[] args) in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 10
   at Program.<Main>(String[] args)
   at System.Environment.CallEntryPoint(IntPtr entryPoint, String[]* pArgument, Int32* pReturnValue, Boolean captureException, Exception* pException)

.NET 11 (async v2 on):

dotnet run -f net11.0
.NET 11.0.0-preview.4.26230.115
Unhandled exception. System.InvalidOperationException: boom
   at Program.<<Main>$>g__MiddleAsync|0_1() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 24
   at Program.<<Main>$>g__OuterAsync|0_0() in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 15
   at Program.<Main>$(String[] args) in /Users/rich/git/build-talk-2026/runtime-async-demo/Program.cs:line 10
--- End of stack trace from previous location ---
   at Program.<Main>(String[] args)
   at System.Environment.CallEntryPoint(IntPtr entryPoint, String[]* pArgument, Int32* pReturnValue, Boolean captureException, Exception* pException)

Both of the .NET 11 examples are different from the .NET 10 baseline.

[richlander]

As a side-note, I was surprised that all the methods are g__. That's due to top-level statements since a class needs to be materialized. That's not a concern but FYI for anyone wondering.

[jkotas]

System.Environment.CallEntryPoint

#127677

[rcj1]

We have filtered out these spurious markers in asyncv1 here:

runtime/src/libraries/System.Private.CoreLib/src/System/Diagnostics/StackTrace.cs

Line 361 in e885bb9

if (sf.IsLastFrameFromForeignExceptionStackTrace && !isAsync)

The issue had been masked because if we resume before throwing, this marker just so happens to land on the DispatchContinuations stack trace hidden method, and we only print the marker if it lands on non-hidden code. I linked the PR to fix this.

[richlander]

Thanks to both of you. These are good fixes to make this new feature look good.

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