SixLabors/ImageSharp · error · InvalidMemoryOperationException

The buffer capacity of the provided MemoryAllocator is…

Error message

The buffer capacity of the provided MemoryAllocator is insufficient for the requested buffer alignment: {alignment}.

What it means

Thrown when a caller requests an aligned buffer but the underlying MemoryAllocator cannot hand out blocks large enough to satisfy the requested alignment — i.e. the allocator's per-buffer capacity is smaller than the alignment. ImageSharp fails fast because aligned-beyond-capacity requests cannot be honored.

Solutions

1. Increase the allocator's buffer capacity (pool block size) so it is >= the requested alignment when constructing the MemoryAllocator.
2. Lower the requested Alignment parameter to a value the allocator can satisfy (e.g. 16 or 32 bytes).
3. Use the default allocator (which has adequate capacity) instead of a custom tightly constrained one for aligned allocations.

Example fix

// before
var allocator = new UniformUnmanagedPoolMemoryAllocator(blockSize: 16);
var buf = allocator.Allocate<byte>(1024, Alignment.Create(64)); // throws
// after
var allocator = new UniformUnmanagedPoolMemoryAllocator(blockSize: 4096);
var buf = allocator.Allocate<byte>(1024, Alignment.Create(64));

if ((int)alignment > allocatorMaxBufferCapacity)
    throw new ArgumentException($"Alignment {alignment} exceeds allocator buffer capacity {allocatorMaxBufferCapacity}");

try { var buf = allocator.Allocate<T>(length, Alignment.Create(64)); }
catch (InvalidMemoryOperationException ex) when (ex.Message.Contains("alignment"))
{ var buf = allocator.Allocate<T>(length); /* unaligned fallback */ }

When it happens

Trigger: Calling MemoryAllocator.Allocate<T>(length, Alignment alignment) (or Allocate2D overloads taking alignment) with an alignment value larger than the allocator's configured maximum buffer capacity (e.g. UniformUnmanagedPoolMemoryAllocator with small pool block sizes).

Common situations: Configuring a small memory pool (e.g. for low-memory environments) and then using SIMD/vectorized code paths that demand 32/64-byte alignment; supplying Alignment from configuration without checking the allocator's capacity.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Attempted to allocate a buffer of length=
• Attempted to allocate a buffer of length=
• No encoder was found for extension
• source
• maxDegreeOfParallelism

AI-assisted analysis of SixLabors/ImageSharp@59ce6af6fc (2026-09-13). Data as JSON: /api/errors/5c842243dd8d5624. Report an issue: GitHub.

Appendix: source

Thrown at src/ImageSharp/Memory/InvalidMemoryOperationException.cs:36

    public InvalidMemoryOperationException(string message)
        : base(message)
    {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="InvalidMemoryOperationException"/> class.
    /// </summary>
    public InvalidMemoryOperationException()
    {
    }

    [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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