Chapter 7. Migration from previous versions of .NET

Microsoft provides instructions for migrating from most previous versions of .NET Core.

If you are using a version of .NET that is no longer supported or want to migrate to a newer .NET version to expand functionality, see the following articles:

Refer to the following Microsoft articles when migrating from .NET Framework:

Several technologies and APIs present in the .NET Framework are not available in .NET Core and .NET. If your application or library requires these APIs, consider finding alternatives or continue using the .NET Framework. .NET Core and .NET do not support the following technologies and APIs:

Additionally, several .NET APIs can only be used in Microsoft Windows environments. The following list shows examples of these Windows-specific APIs:

Consider using the .NET Portability Analyzer to identify API gaps and potential replacements.

For example, enter the following command to find out how much of the API used by your .NET Framework application is supported by .NET 5.0:

dotnet /path/to/ApiPort.dll analyze -f . -r html --target '.NET Framework,Version=<dotnet-framework-version>' --target '.NET Core,Version=<dotnet-version>'

$ dotnet /path/to/ApiPort.dll analyze -f . -r html --target '.NET Framework,Version=<dotnet-framework-version>' --target '.NET Core,Version=<dotnet-version>'

Replace <dotnet-framework-version> with the .NET Framework version you are currently using. For example, 4.6. Replace <dotnet-version> with the version of .NET Core you plan to migrate to. For example, 3.1.