SixLabors/ImageSharp · error · InvalidImageContentException

Marker has bad length .

Error message

Marker {marker} has bad length {length}.

What it means

JpegThrowHelper.ThrowBadMarker throws InvalidImageContentException when a JPEG marker segment declares a length that does not match what the decoder requires for that marker type (e.g. an SOFn/SOs/DQT segment whose stated length is impossible). It means the stream structure violates the JPEG (ITU T.81) specification.

Solutions

1. Re-obtain the image from a trusted source and validate checksums if available.
2. Catch InvalidImageContentException in batch pipelines and skip/quarantine the offending file.
3. Re-encode the file with a standard encoder if the original producer is at fault.
4. If decoding untrusted input, add the file to a rejection report instead of letting it crash the worker.

Example fix

// before
using var image = Image.LoadAsync(stream);
// after
try { using var image = await Image.LoadAsync(stream); }
catch (InvalidImageContentException ex)
{
    quarantine(stream, $"Bad marker: {ex.Message}");
}

try
{
    using var image = await Image.LoadAsync(stream);
}
catch (InvalidImageContentException ex)
{
    quarantine(stream, ex.Message); // bad marker length
}

When it happens

Trigger: Decoding a JPEG where a marker segment (identified by the marker parameter, e.g. "SOF0", "DQT") has a declared segment length inconsistent with the component count or table size the decoder derives — corrupt or hand-crafted streams, truncation mid-segment.

Common situations: Corrupted downloads/uploads; files processed by buggy third-party encoders; fuzzed or malicious input in image-processing services; byte-level file corruption on disk.

Related errors

• Bad Quantization Table index
• Unknown Quantization Table precision
• Bad sampling factor.
• {errorMessage}
• Input stream does not have enough bytes to parse declared…

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/ecf8ec8b9fa219a2. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Formats/Jpeg/JpegThrowHelper.cs:12

// Copyright (c) Six Labors.
// Licensed under the Six Labors Split License.

namespace SixLabors.ImageSharp.Formats.Jpeg;

internal static class JpegThrowHelper
{
    public static void ThrowNotSupportedException(string errorMessage) => throw new NotSupportedException(errorMessage);

    public static void ThrowInvalidImageContentException(string errorMessage) => throw new InvalidImageContentException(errorMessage);

    public static void ThrowBadMarker(string marker, int length) => throw new InvalidImageContentException($"Marker {marker} has bad length {length}.");

    public static void ThrowNotEnoughBytesForMarker(byte marker) => throw new InvalidImageContentException($"Input stream does not have enough bytes to parse declared contents of the {marker:X2} marker.");

    public static void ThrowBadQuantizationTableIndex(int index) => throw new InvalidImageContentException($"Bad Quantization Table index {index}.");

    public static void ThrowBadQuantizationTablePrecision(int precision) => throw new InvalidImageContentException($"Unknown Quantization Table precision {precision}.");

    public static void ThrowBadSampling() => throw new InvalidImageContentException("Bad sampling factor.");

    public static void ThrowBadSampling(int factor) => throw new InvalidImageContentException($"Bad sampling factor: {factor}");

    public static void ThrowBadProgressiveScan(int ss, int se, int ah, int al) => throw new InvalidImageContentException($"Invalid progressive parameters Ss={ss} Se={se} Ah={ah} Al={al}.");

    public static void ThrowInvalidImageDimensions(int width, int height) => throw new InvalidImageContentException($"Invalid image dimensions: {width}x{height}.");

    public static void ThrowDimensionsTooLarge(int width, int height) => throw new ImageFormatException($"Image is too large to encode at {width}x{height} for JPEG format.");

    public static void ThrowNotSupportedComponentCount(int componentCount) => throw new NotSupportedException($"Images with {componentCount} components are not supported.");

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