SixLabors/ImageSharp · error · InvalidMemoryOperationException

Attempted to allocate a buffer of length=

Error message

Attempted to allocate a buffer of length={requestedLength} that would increase the accumulative allocation size to {totalLength}, exceeding the limit {limit}.

What it means

Like the single-buffer limit throw, this fires when a requested allocation is over the accumulative limit: granting it would push the allocator's TOTAL outstanding allocation size above the configured cap. It protects against cumulative memory exhaustion across many buffers, e.g. during large multi-buffer decodes.

Solutions

1. Increase the accumulative AllocationLimit in the allocator configuration to cover the real concurrent working set.
2. Reduce concurrency (process images sequentially or with fewer parallel tasks) so outstanding allocations stay under the limit.
3. Dispose images/buffers promptly (using statements) so returned memory lowers the accumulative total before new requests.

Example fix

// before
// limit 256MB, concurrency 32 -> total requests exceed limit
Parallel.ForEach(files, f => using-image-load(f));
// after
// raise limit and/or limit parallelism
Parallel.ForEach(files, new ParallelOptions { MaxDegreeOfParallelism = 8 }, f => using-image-load(f));

try { using var image = Image.Load(config, stream); }
catch (InvalidMemoryOperationException ex) when (ex.Message.Contains("accumulative"))
{ /* reduce concurrency or raise the accumulative limit and retry */ }

When it happens

Trigger: Any allocation request where (currently tracked total + requestedLength) > AllocationLimit — commonly while decoding large images whose decoders allocate several big buffers, or under sustained concurrent image processing sharing one limited allocator.

Common situations: Server workloads processing many large images concurrently under one memory-limited Configuration; large panoramas/mosaics whose decode needs multiple buffers that together exceed the cap; limits set for one workload then applied to a heavier one.

Understand the failure class

Background: "File too large" / "file size exceeds limit" errors: why libraries cap file sizes and how to fix them — this error's family across 46 libraries.

Related errors

• Attempted to allocate a buffer of length=
• The buffer capacity of the provided MemoryAllocator is…
• No encoder was found for extension
• source
• maxDegreeOfParallelism

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/d10401cb0e778fb6. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Memory/InvalidMemoryOperationException.cs:45

    {
    }

    [DoesNotReturn]
    internal static void ThrowNegativeAllocationException(long length) =>
        throw new InvalidMemoryOperationException($"Attempted to allocate a buffer of negative length={length}.");

    [DoesNotReturn]
    internal static void ThrowInvalidAlignmentException(long alignment) =>
        throw new InvalidMemoryOperationException(
                $"The buffer capacity of the provided MemoryAllocator is insufficient for the requested buffer alignment: {alignment}.");

    [DoesNotReturn]
    internal static void ThrowAllocationOverLimitException(ulong length, long limit) =>
            throw new InvalidMemoryOperationException($"Attempted to allocate a buffer of length={length} that exceeded the limit {limit}.");

    [DoesNotReturn]
    internal static void ThrowAccumulativeAllocationOverLimitException(long requestedLength, long totalLength, long limit) =>
            throw new InvalidMemoryOperationException(
                $"Attempted to allocate a buffer of length={requestedLength} that would increase the accumulative allocation size to {totalLength}, exceeding the limit {limit}.");
}

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