Migrate solution file from .sln to .slnx format

[stefannikolei]

Fixes #8096

Changes

Migrate akka.sln to akka.slnx

[stefannikolei]

I am a bit lost on the build errors..

[stefannikolei]

Isn't this version out of support?

[Arkatufus]

its the minimum SDK version that supports .slnx format

[Aaronontheweb]

Answer is in the build logs:

❯ fail: Incrementalist.Cmd.Program[0]
      Command 'dotnet test -c Release --no-build --framework net8.0 --logger:trx --results-directory TestResults
/home/vsts/work/1/s/src/contrib/cluster/Akka.Cluster.Sharding.Tests/Akka.Cluster.Sharding.Tests.csproj' failed for
/home/vsts/work/1/s/src/contrib/cluster/Akka.Cluster.Sharding.Tests/Akka.Cluster.Sharding.Tests.csproj with exit
code 1 after 00:00:01.0198591
info: Incrementalist.Cmd.Program[0]
      Executing 'dotnet test -c Release --no-build --framework net8.0 --logger:trx --results-directory TestResults
/home/vsts/work/1/s/src/core/Akka.Tests/Akka.Tests.csproj' for
/home/vsts/work/1/s/src/core/Akka.Tests/Akka.Tests.csproj
Test run for /home/vsts/work/1/s/src/core/Akka.Tests/bin/Release/net8.0/Akka.Tests.dll (.NETCoreApp,Version=v8.0)
VSTest version 18.0.1 (x64)
Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
Testhost process for source(s) '/home/vsts/work/1/s/src/core/Akka.Tests/bin/Release/net8.0/Akka.Tests.dll' exited
with error: You must install or update .NET to run this application.
App: /home/vsts/work/1/s/src/core/Akka.Tests/bin/Release/net8.0/testhost.dll
Architecture: x64
Framework: 'Microsoft.NETCore.App', version '8.0.0' (x64)
.NET location: /opt/hostedtoolcache/dotnet/
The following frameworks were found:
  10.0.1 at [/opt/hostedtoolcache/dotnet/shared/Microsoft.NETCore.App]
Learn more:
https://aka.ms/dotnet/app-launch-failed
To install missing framework, download:
https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=8.0.0&arch=x64&rid=linux-x64
&os=ubuntu.24.04
. Please check the diagnostic logs for more information.
Results File: /home/vsts/work/1/s/TestResults/_runnervmzqwse_2026-03-13_22_31_06.trx
Test Run Aborted.
fail: Incrementalist.Cmd.Program[0]
      Command 'dotnet test -c Release --no-build --framework net8.0 --logger:trx --results-directory TestResults
/home/vsts/work/1/s/src/core/Akka.Tests/Akka.Tests.csproj' failed for
/home/vsts/work/1/s/src/core/Akka.Tests/Akka.Tests.csproj with exit code 1 after 00:00:01.0316801
info: Incrementalist.Cmd.Program[0]
      Executing 'dotnet test -c Release --no-build --framework net8.0 --logger:trx --results-directory TestResults
/home/vsts/work/1/s/src/core/Akka.Remote.Tests/Akka.Remote.Tests.csproj' for
/home/vsts/work/1/s/src/core/Akka.Remote.Tests/Akka.Remote.Tests.csproj
Test run for /home/vsts/work/1/s/src/core/Akka.Remote.Tests/bin/Release/net8.0/Akka.Remote.Tests.dll
(.NETCoreApp,Version=v8.0)

The tests / code samples / etc need to be upgraded to target .NET 10 also.

akka.net/Directory.Build.props

Line 35 in 117330d

<NetTestVersion>net8.0</NetTestVersion>

- if changing that should fix it.

[stefannikolei]

So. Tests should target .net10? But should net8 apps compile fine with a net10 sdk?

[Aaronontheweb]

It's a runtime issue - there's no .NET 8 runtime installed now that global.json targets .NET 10. Better to just not need .NET 8 any more. This is a testing-only change