NuGet Warning NU5124

The license identifier 'Microsoft-SpecialLicense' is not recognized by the current toolset.

Issue

The NuGet Client tools have a known list of license identifiers. As this knowledge is contained within the product, sometimes version of the tools is not aware of the standardization of the license. Other times, the license simply is not a standardized license, with no clear timeline of ever becoming one.

Solution

Use an updated client that understands the license identifier you are trying to use. Use a license file instead of an expression if there is no timeline for the said license to become an SPDX standard license.