Build fails on .NET SDK 10.0.400: NuGet.Packaging 6.14.3 conflicts with the SDK's NuGet 7.x

[ChrisonSimtian]

Problem

global.json pins SDK 10.0.100 with rollForward: latestMinor, so CI now runs SDK 10.0.400. That SDK loads NuGet.Frameworks 7.9.0.0 into MSBuild. Directory.Packages.props:21 pins NuGet.Packaging 6.14.3, which loads NuGet.Frameworks 6.14.3 into the same process. Every ./build.sh run fails at Compile, so CI fails on main and on every PR.

Outcome

./build.sh Compile succeeds on SDK 10.0.400, and the required ubuntu-latest check passes again.

Acceptance criteria

• NuGet.Packaging is bumped to a 7.x version matching the NuGet version shipped by the supported SDK range.
• ./build.sh Compile and ./build.sh Test pass locally on SDK 10.0.400.
• ubuntu-latest is green on main.

Notes

Nothing in the repository changed. The last green run used SDK 10.0.302. The first failing run used 10.0.400.

Error: InvalidProjectFileException: The expression "[MSBuild]::GetTargetFrameworkIdentifier(net10.0)" cannot be evaluated. Could not load file or assembly 'NuGet.Frameworks, Version=7.9.0.0'.

NuGet 7.0 only removed APIs that were already marked obsolete. This repo uses NuspecReader, PackageArchiveReader, PackageFolderReader, VersionRange, NuGetVersion and NuGetFramework. None of them are affected. Bumping to 7.9.0 was tested locally and compiles with 0 errors.

Open questions

• NuGet 7.x dropped netstandard2.0 support. Fallout.Tooling (net10.0;netstandard2.0) and Fallout.Tooling.Generator (netstandard2.0) then restore .NET Framework assets instead, which produces 35 NU1701 warnings. Do those netstandard2.0 targets still need to exist?
• Pinning 6.14.3 for only the netstandard2.0 target does not work while CentralPackageTransitivePinningEnabled is true (Directory.Packages.props:4).

[ChrisonSimtian]

Direction on the netstandard2.0 open question: we drop it.

NuGet 7.x forces this, and dropping netstandard2.0 means cutting .NET Framework support along with it. That is acceptable. Other PRs already in flight remove the same targets, so this is not a one-off decision made just to unblock the build.

Consequence for the release line: dropping netstandard2.0 and .NET Framework is a breaking change, so the next release may not be 10.5. It would become the 2026 calendar-version release instead, as a deliberate breaking-changes release.

That would pull the calendar-versioning North Star forward. See #637, which records semver 10.x as the current state and CalVer as the target.

[magnusbakken]

We were hit by this one in our customized NukeBuild project, which we're in the process of converting to Fallout. At the moment we've worked around it by pinning NuGet.Packaging to 7.9.0, which seems to work fine for now.

[ChrisonSimtian]

We were hit by this one in our customized NukeBuild project, which we're in the process of converting to Fallout. At the moment we've worked around it by pinning NuGet.Packaging to 7.9.0, which seems to work fine for now.

it should be fine for the most part, there is only a few netstandard2.0 projects left in Fallout and you probably dont use any of those :-) We're in the process of migrating those onto the 2.1 stack hopefully with the next major release