NuGet locks directory moved on Linux

Starting in .NET SDK 11.0.200, NuGet uses ~/.nuget/locks instead of /tmp/NuGetScratch{username}/locks for inter-process locks on Linux. Concurrent NuGet processes that use different lock directories don't coordinate access to shared files.

Version introduced

.NET SDK 11.0.200

Previous behavior

Previously, NuGet used /tmp/NuGetScratch{username}/locks for inter-process locks on Linux, unless you set the NUGET_SCRATCH environment variable.

New behavior

Starting in .NET SDK 11.0.200, NuGet uses ~/.nuget/locks for inter-process locks on Linux, unless you set NUGET_SCRATCH. The ~ represents the user's home directory.

If SDK versions older than 11.0.200 and SDK versions 11.0.200 or later restore concurrently with different lock directories, they don't coordinate access to the global packages folder and other NuGet files. Failures or undefined behavior can result.

In every version, NUGET_SCRATCH overrides the default location. Its value specifies the parent directory, without a trailing locks component; NuGet uses the locks subdirectory within that directory.

Type of breaking change

This change is a behavioral change.

Reason for change

To prevent other users on shared Linux computers from blocking NuGet for a target account, NuGet now stores locks in the user's home directory. The previous predictable path under the shared /tmp directory allowed other users to block NuGet for that account.

Recommended action

To ensure concurrent restores coordinate access to shared files, use .NET SDK 11.0.200 or later everywhere, even for projects that specify an earlier TargetFramework.

Alternatively, set the same NUGET_SCRATCH value for all concurrent NuGet processes, regardless of SDK version. Specify the parent directory without a trailing locks component. For more information, see NuGet environment variables.

Affected APIs

None.