dotnet/wpf · error · FileFormatException

SR.CFRCorruptStgFollowStm

Error message

SR.CFRCorruptStgFollowStm

What it means

While Load walks the reference's path segments, storage and stream components must be ordered storages-first, stream-last. A Storage entry appearing after a stream name means the path is malformed (nothing can live under a stream), so Load throws FileFormatException(SR.CFRCorruptStgFollowStm).

Solutions

  1. Regenerate the package from its source — the serialized path is structurally invalid.
  2. Check the producing writer's reference serialization for storage/stream ordering bugs.
  3. If parsing third-party files, reject them up front with your own structural validation.
  4. Diff the record bytes against a known-good reference to find where ordering broke.

Example fix

// before: blind deserialization of untrusted references
var r = CompoundFileReference.Load(binaryReader);

// after: pre-validate ordering of path components
ValidateReferencePathOrder(rawBytes); // storage... then stream last
var r = CompoundFileReference.Load(binaryReader);
Defensive patterns

Strategy: validation

Validate before calling

bool PathOrderIsValid(IList<(bool isStorage)> segs) { bool sawStream = false; foreach (var s in segs) { if (!s.isStorage) sawStream = true; else if (sawStream) return false; } return true; }

Try / catch

try { var r = CompoundFileReference.Load(reader); } catch (FileFormatException) { RejectMalformedReference(source); }

Prevention

When it happens

Trigger: Load reads a RefComponentType.Storage entry after already having read a stream name — i.e. the serialized path looks like \storage\stream\storage. Caused by corrupt data or a writer emitting entries in the wrong order.

Common situations: Hand-crafted or fuzzed compound files; writers that serialize path segments out of order; byte-level corruption reordering records; mixed-version writer/reader format drift.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/143a396364ddf5c3. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/WindowsBase/MS/Internal/IO/Packaging/CompoundFile/CompoundFileReference.cs:190

            // type is encountered
            StringCollection storageList = null;
            String streamName = null;

            // loop through the entries - accumulating strings until we know what kind of object
            // we ultimately need
            int byteLength;     // reusable
            while (entryCount > 0)
            {
                // first Int32 tells us what kind of component this entry represents
                RefComponentType refType = (RefComponentType)reader.ReadInt32();
                bytesRead += ContainerUtilities.Int32Size;

                switch (refType)
                {
                    case RefComponentType.Storage:
                    {
                        if (streamName != null)
                            throw new FileFormatException(
                                SR.CFRCorruptStgFollowStm);

                        if (storageList == null)
                            storageList = new StringCollection();

                        String str = ContainerUtilities.ReadByteLengthPrefixedDWordPaddedUnicodeString(reader, out byteLength);
                        bytesRead += byteLength;
                        storageList.Add(str);
} break;
                    case RefComponentType.Stream:
                    {
                        if (streamName != null)
                            throw new FileFormatException(
                                SR.CFRCorruptMultiStream);

                        streamName = ContainerUtilities.ReadByteLengthPrefixedDWordPaddedUnicodeString(reader, out byteLength);
                        bytesRead += byteLength;
                    } break;

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