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SYSLIB0040: EncryptionPolicy.NoEncryption and EncryptionPolicy.AllowNoEncryption are obsolete

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EncryptionPolicy.NoEncryption and EncryptionPolicy.AllowNoEncryption are marked as obsolete, starting in .NET 7. Using these enumeration fields in code generates warning SYSLIB0040 at compile time.

Older SSL/TLS versions permitted no encryption, and while it may be useful for debugging, it shouldn't be used in production. In addition, NULL encryption is no longer available as of TLS 1.3.

Workaround

N/A

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 SYSLIB0040

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

// Re-enable the warning.
#pragma warning restore SYSLIB0040

To suppress all the SYSLIB0040 warnings in your project, add a <NoWarn> property to your project file.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   ...
   <NoWarn>$(NoWarn);SYSLIB0040</NoWarn>
  </PropertyGroup>
</Project>

For more information, see Suppress warnings.