SixLabors/ImageSharp · error · InvalidOperationException

This method is used for AOT code generation only. Do not…

Error message

This method is used for AOT code generation only. Do not call it at runtime.

What it means

AotCompilerTools.SeedPixelFormats exists solely so the AOT compiler can generate code for all built-in pixel formats at publish time. If it is ever executed at runtime it deliberately throws InvalidOperationException because its body is not meant to run and its catch-all swallows the seeding calls.

Solutions

1. Remove the runtime call — it is only for AOT compilation (dotnet publish with AOT), never runtime
2. If you need pixel-format seeding at runtime, nothing is required: the library seeds formats lazily on first use
3. Exclude the call from test harnesses that enumerate and invoke public static methods

Example fix

// before
AotCompilerTools.SeedPixelFormats(); // in startup code
// after
// removed — this method is only consumed by the AOT compiler during publish

if (Environment.GetEnvironmentVariable("CI") is not null && callingSeeding) throw new NotSupportedException("SeedPixelFormats is AOT-only");

try { AotCompilerTools.SeedPixelFormats(); }
catch (InvalidOperationException) { /* AOT-only method invoked at runtime — remove the call */ }

When it happens

Trigger: Explicitly calling AotCompilerTools.SeedPixelFormats() in normal runtime code; calling it in unit tests or reflection-based tooling instead of letting the AOT toolchain consume it.

Common situations: Misunderstanding the API's purpose when doing ahead-of-time trimming on iOS/WebAssembly/Unity IL2CPP; accidentally invoking all public methods of a class in a smoke test; copy-pasting AOT seeding code into a startup path.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Cannot read from the stream.
• {message}
• (invalid memory operation)
• Image cannot be loaded. Available decoders
• Could not find any converter for JpegColorSpace

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/09e373dba676f0d6. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Advanced/AotCompilerTools.cs:131

            Seed<Rgb48>();
            Seed<Rgb96>();
            Seed<Rgba1010102>();
            Seed<Rgba128>();
            Seed<Rgba32>();
            Seed<Rgba32P>();
            Seed<Rgba64>();
            Seed<RgbaHalf>();
            Seed<RgbaHalfP>();
            Seed<RgbaVector>();
            Seed<Short2>();
            Seed<Short4>();
        }
        catch
        {
            // nop
        }

        throw new InvalidOperationException("This method is used for AOT code generation only. Do not call it at runtime.");
    }

    /// <summary>
    /// Seeds the modern .NET AOT compiler with bulk pixel operations for every built-in pixel format.
    /// </summary>
    /// <exception cref="InvalidOperationException">
    /// This method is used for AOT code generation only. Do not call it at runtime.
    /// </exception>
    [Preserve]
    public static void SeedPixelOperations()
    {
        try
        {
            // Keep this inventory finite and explicit. ImageSharp cannot precompile consumer-defined pixel types, while
            // these closed calls make every built-in specialization visible without retaining the much larger legacy seed graph.
            AotCompilePixelOperations<A8>();
            AotCompilePixelOperations<Argb32>();
            AotCompilePixelOperations<Argb32P>();

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