SixLabors/ImageSharp · error · InvalidImageContentException

PNG Image does not contain a data chunk.

Error message

PNG Image does not contain a data chunk.

What it means

Thrown during PNG decoding when the stream ends without any IDAT (image data) chunk having been encountered. It is a sentinel guard in a validation helper (ThrowNoData), not tied to a specific corrupt payload: the decoder finished chunk iteration and reached the IEND/end of stream with zero data chunks, so no pixel data exists to reconstruct. The input is a truncated or chunk-stripped file (or not a real PNG at all) that passed the header check but is reported as an InvalidImageContentException.

Solutions

1. Verify the file is complete: it should end with an IEND chunk and contain at least one IDAT chunk.
2. Re-download or re-export the image and retry the decode.
3. Check the stream wasn't partially read or copied (compare byte counts / file size).
4. Catch InvalidImageContentException and treat the input as unusable.

Example fix

// before
using var image = Image.Load(downloadedStream);
// after
if (downloadedStream.Length < expectedMinSize)
    throw new InvalidOperationException("Download incomplete");
using var image = Image.Load(downloadedStream);

// Ensure the transfer completed: e.g. compare size against source metadata
if (fileInfo.Length < sourceSize)
    throw new InvalidOperationException("Image download incomplete");

try
{
    using var image = Image.Load(stream);
}
catch (InvalidImageContentException ex) when (ex.Message.Contains("data chunk"))
{
    // no IDAT — file is truncated or metadata-only
}

When it happens

Trigger: Decoding a PNG that has IHDR but zero IDAT chunks — e.g. metadata-only files, files truncated right after the header, or encoders that wrote no image data before IEND.

Common situations: Interrupted downloads or uploads, streaming decodes where the reader consumed only part of the file, malformed files produced by buggy encoders or image-processing pipelines.

Related errors

• PNG Image must contain a header chunk and it must be…
• {errorMessage}
• APNG Image does not contain a default data chunk.
• Invalid PNG data.
• {message}

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/8b0610a3f8774e24. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Formats/Png/PngThrowHelper.cs:18

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

using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;

namespace SixLabors.ImageSharp.Formats.Png;

internal static class PngThrowHelper
{
    [DoesNotReturn]
    public static void ThrowInvalidImageContentException(string errorMessage) => throw new InvalidImageContentException(errorMessage);

    [DoesNotReturn]
    public static void ThrowInvalidHeader() => throw new InvalidImageContentException("PNG Image must contain a header chunk and it must be located before any other chunks.");

    [DoesNotReturn]
    public static void ThrowNoData() => throw new InvalidImageContentException("PNG Image does not contain a data chunk.");

    [DoesNotReturn]
    public static void ThrowMissingDefaultData() => throw new InvalidImageContentException("APNG Image does not contain a default data chunk.");

    [DoesNotReturn]
    public static void ThrowInvalidAnimationControl() => throw new InvalidImageContentException("APNG Image must contain a acTL chunk and it must be located before any IDAT and fdAT chunks.");

    [DoesNotReturn]
    public static void ThrowMissingFrameControl() => throw new InvalidImageContentException("One of APNG Image's frames do not have a frame control chunk.");

    [DoesNotReturn]
    public static void ThrowMissingPalette() => throw new InvalidImageContentException("PNG Image does not contain a palette chunk.");

    [DoesNotReturn]
    public static void ThrowInvalidChunkType() => throw new InvalidImageContentException("Invalid PNG data.");

    [DoesNotReturn]
    public static void ThrowInvalidChunkType(string message) => throw new InvalidImageContentException(message);

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