.NET 8 MAUI Blazor Hybrid iOS Release Build Fails with NullabilityInfoContext Error

Below is one recommended workaround for this issue. It turns out that the required metadata for System.Reflection.NullabilityInfoContext is getting trimmed out in Release mode during linking. This means that even though you’re setting the AppContext switch, the type’s metadata isn’t available at runtime.

A common solution is to instruct the linker not to remove that type. For example, you can create a linker configuration file (commonly named LinkerConfig.xml) with the following content:

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<linker>
  <assembly fullname="System.Private.CoreLib">
    <type fullname="System.Reflection.NullabilityInfoContext" preserve="all" />
  </assembly>
</linker>

Then add an item reference in your iOS project’s csproj file so the linker picks it up:

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<ItemGroup>
  <TrimmerRootDescriptor Include="LinkerConfig.xml" />
</ItemGroup>

This tells the linker to preserve all metadata for System.Reflection.NullabilityInfoContext so that System.Text.Json can obtain the needed nullability info.

Alternatively, you can temporarily disable trimming (linking) for Release mode to confirm that trimming is causing the issue, but note that this may affect your app’s size and performance. To disable linking, set the following property in your csproj:

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<PropertyGroup>
  <MtouchLink>None</MtouchLink>
</PropertyGroup>

Remember that disabling the linker entirely isn’t the recommended long-term solution. Instead, applying a linker configuration such as the one above should let you keep trimming enabled while preserving just what’s needed.

This approach has helped others resolve the error when trying to serialize using System.Text.Json in Release mode on iPads for .NET 8 Maui Blazor Hybrid applications.