dotnet/wpf · error · ArgumentException

Buffer size is too small to accommodate the specified…

Error message

Buffer size is too small to accommodate the specified parameters.

What it means

ByteStream.Read requires the supplied buffer to be non-empty and large enough to hold count bytes starting at offset: (buffer.Length > 0) && ((buffer.Length - offset) >= count). Otherwise it throws ArgumentException(SR.BufferTooSmall) naming the buffer parameter, before any IStream read occurs.

Solutions

1. Clamp count: count = Math.Min(count, buffer.Length - offset) before calling Read.
2. Ensure offset + count <= buffer.Length by construction in copy loops.
3. Allocate a buffer at least count bytes long when a full read is intended.

Example fix

// before
stream.Read(buf, offset, requestedCount); // ArgumentException if too small
// after
int count = Math.Min(requestedCount, buf.Length - offset);
if (count > 0) stream.Read(buf, offset, count);

if (buf.Length == 0 || count > buf.Length - offset) count = Math.Max(0, buf.Length - offset);

try { stream.Read(buf, offset, count); }
catch (ArgumentException ex) when (ex.ParamName == "buffer") { count = buf.Length - offset; stream.Read(buf, offset, count); }

When it happens

Trigger: Calling Read with buffer.Length < offset + count, e.g. buffer.Length == 0 with count > 0, or reading exactly the remaining chunk after the last chunk partially filled the buffer.

Common situations: Chunked-read loops that forget to shrink count for the final partial chunk; reusing small scratch buffers with oversized counts.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• ' ' is not a valid value for this control.
• Buffer offset cannot be negative.
• Cannot have leading path delimiter.
• CompoundFile path must be non-empty.
• Count of bytes to read cannot be negative.

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/ef784698f2b44b7d. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Internal/IO/Packaging/ByteStream.cs:279

            // count has to be positive number
            if (0 > count)
            {
                throw new ArgumentOutOfRangeException(nameof(count),
                                                      SR.ReadCountNegative);
            }

            // offset has to be a positive number
            if (0 > offset)
            {
                throw new ArgumentOutOfRangeException(nameof(offset),
                                                      SR.BufferOffsetNegative);
            }

            // make sure that we have a buffer that matches number of bytes we need to read 
            // since all values are > 0, there is no chance of overflow
            if (!((buffer.Length > 0) && ((buffer.Length - offset) >= count)))
            {
                throw new ArgumentException(SR.BufferTooSmall, nameof(buffer));
            }
            
            // offset == 0 is the normal case
            if (0 == offset)
            {
                _securitySuppressedIStream.Read(buffer, count, out read);
            }
            // offset involved.  Must be positive
            else if (0 < offset)
            {
                // Read into local array and then copy it into the given buffer at
                //  the specified offset.
                byte[] localBuffer = new byte[count];

                _securitySuppressedIStream.Read(localBuffer, count, out read);

                if (read > 0)
                {

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