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SYSLIB0056: Assembly.LoadFrom that takes an AssemblyHashAlgorithm is obsolete

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The overload of Assembly.LoadFrom that takes an AssemblyHashAlgorithm is obsolete, starting in .NET 9. Calling it in code generates warning SYSLIB0056 at compile time.

Reason for obsoletion

Assembly.LoadFrom(String, Byte[], AssemblyHashAlgorithm) unconditionally throws a NotSupportedException. This is a poor development experience. The overload looks like a valid API until it's used, and it throws at run time. Marking it as obsolete gives the necessary design-time signal to not use it.

Workaround

Use an overload of Assembly.LoadFrom that doesn't take an AssemblyHashAlgorithm.

Suppress a warning

If you must use the obsolete APIs, you can suppress the warning in code or in your project file.

To suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the warning.

// Disable the warning.
#pragma warning disable SYSLIB0056

// Code that uses obsolete API.
// ...

// Re-enable the warning.
#pragma warning restore SYSLIB0056

To suppress all the SYSLIB0056 warnings in your project, add a <NoWarn> property to your project file.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   ...
   <NoWarn>$(NoWarn);SYSLIB0056</NoWarn>
  </PropertyGroup>
</Project>

For more information, see Suppress warnings.