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SYSLIB0022: The Rijndael and RijndaelManaged types are obsolete

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The Rijndael and RijndaelManaged types are marked as obsolete, starting in .NET 6. Using them in code generates warning SYSLIB0022 at compile time.

Workarounds

Use System.Security.Cryptography.Aes instead.

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 SYSLIB0022

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

// Re-enable the warning.
#pragma warning restore SYSLIB0022

To suppress all the SYSLIB0022 warnings in your project, add a <NoWarn> property to your project file.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   ...
   <NoWarn>$(NoWarn);SYSLIB0022</NoWarn>
  </PropertyGroup>
</Project>

For more information, see Suppress warnings.