.NET Framework 4.0 no longer supported

[pablo-msft]

https://github.com/microsoft/cpp_client_telemetry/blob/main/docs/cpp-start-windows.md#option-1-build-the-sdk-from-source-using-visual-studio
Open cpp_client_telemetry/Solutions/MSTelemetrySDK.sln in Visual Studio 2022 (note that 2022 is not on the prereqs list). Get pop-up:

[maxgolov]

Just right-click and unload the unsupported project. Those who still need it would open it would build with an older compiler. Toolchain version can be passed via the build script.

[bmehta001]

Addressed by #1458 (merged into main on 2026-07-01):

• The VS2022/VS2026 command-line build wrappers (build-all-v143.bat, build-all-v145.bat, build-all-windows.bat) and the build-windows-vs2022 CI workflow now set SKIP_NET40_BUILD=1, so scripted/CI builds skip the legacy .NET Framework 4.0 targets.
• docs/cpp-start-windows.md now documents that Visual Studio 2022+ may report the legacy net40/SampleCsNet40 projects as unsupported, that the command-line wrappers skip them, and that they can be unloaded in the IDE when building the native SDK.

The net40 projects are intentionally retained for legacy .NET Framework wrapper support, so the IDE prompt is expected behavior rather than a defect — consistent with the guidance to unload the unsupported project. Closing as resolved; please reopen if you'd prefer the net40 projects be excluded from the default solution entirely.