dotnet/wpf · error · ApplicationException

SR.ResourceTooBig (ResourceTooBig: , max )

Error message

SR.ResourceTooBig (ResourceTooBig: {_sourcePath}, max {Int32.MaxValue})

What it means

ResourcesGenerator's LazyFileStream wraps a resource file opened for reading and, because resource data is later copied into int-sized buffers, limits the file to Int32.MaxValue bytes. If the source stream is longer, it throws ApplicationException with SR.ResourceTooBig naming the file and the 2GB limit.

Solutions

Remove or shrink the oversized resource file so it is under 2 GB.
Exclude large assets from the resource list and load them from disk at runtime instead.
Check for accidentally included build outputs (e.g. a huge .resources or database file) in the resource items.
If truly needed, split the content into multiple resources or store it outside the assembly.

Example fix

<!-- before -->
<Resource Include="Assets\huge-video.mp4" />
<!-- after -->
<!-- copy file to output dir and load at runtime -->
<None Include="Assets\huge-video.mp4" CopyToOutputDirectory="PreserveNewest" />

Defensive patterns

Strategy: validation

Validate before calling

var fi = new FileInfo(resourcePath);
if (fi.Length > int.MaxValue)
    throw new InvalidOperationException($"Resource {resourcePath} exceeds 2GB in-process limit ({fi.Length} bytes)");

Try / catch

try { generator.Generate(...); }
catch (ApplicationException ex) when (ex.Message.Contains("ResourceTooBig") || ex.Message.Contains("too big"))
{ log.Error("Resource exceeds Int32.MaxValue; shrink or exclude it", ex); throw; }

Prevention

Audit Resource items for large binaries (video, DB dumps, build artifacts)
Ship big assets as loose files, not embedded resources
Set CI checks on resource file sizes

When it happens

Trigger: Building WPF .resources (.baml/resource embedding) where a source resource file (e.g. a large image, media, or .resources blob passed to GenerateResource/ResourceGenerating pipeline) exceeds 2,147,483,647 bytes.

Common situations: Projects that accidentally embed very large videos, high-resolution multi-gigabyte images, or stale build artifacts as resources.

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

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/e3d4ada5ed5d50ce. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/Microsoft/Build/Tasks/Windows/ResourcesGenerator.cs:53

            public LazyFileStream(string path)
            {
                _sourcePath = Path.GetFullPath(path);
            }

            private Stream SourceStream
            {
                get
                {
                    if (_sourceStream == null)
                    {
                        _sourceStream = new FileStream(_sourcePath, FileMode.Open, FileAccess.Read, FileShare.Read);

                        // limit size to System.Int32.MaxValue
                        long length = _sourceStream.Length;
                        if (length > (long)System.Int32.MaxValue)
                        {
                            throw new ApplicationException(SR.Format(SR.ResourceTooBig, _sourcePath, System.Int32.MaxValue));
                        }

                    }
                    return _sourceStream;
                }
            }

            public override bool CanRead { get { return true; } }

            public override bool CanSeek { get { return true; } }

            public override bool CanWrite { get { return false; } }

            public override void Flush() {}

            public override long Length
            {
                get { return SourceStream.Length; }

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