NuGet Error NU1019

Scenario

The project 'MyProject' contains a TargetFramework 'net10.0/benchmark' with disallowed characters. TargetFramework names must contain only ASCII characters and must not contain path separators.

Issue

Your project file has a TargetFramework or TargetFrameworks value that contains disallowed characters. NuGet doesn't allow the following characters in target framework names:

• Path separators (/ or \): These characters break the assets file format and are always disallowed.
• Non-ASCII characters: Target framework names must contain only ASCII characters (characters with a value of 127 or less).

This validation is gated behind the SdkAnalysisLevel property:

• SDK analysis level 10.0.300 or later: Path separators in target framework names raise an error. Non-ASCII characters raise a warning.
• SDK analysis level 11.0.100 or later: Both path separators and non-ASCII characters raise an error.

Solution

Rename the target framework values in your project file to use only ASCII characters and remove any path separators.

For example, change:

<PropertyGroup>
  <TargetFramework>net10.0/benchmark</TargetFramework>
</PropertyGroup>

To a valid target framework name:

<PropertyGroup>
  <TargetFramework>net10.0-benchmark</TargetFramework>
</PropertyGroup>