hyperledger/fabric · error

error while reading from snapshot file: %s

Error message

error while reading from snapshot file: %s

What it means

FileReader.DecodeUVarInt wraps any error returned by binary.ReadUvarint (EOF, unexpected EOF, corrupted varint) with the snapshot file name. It signals that a variable-length integer could not be read from the snapshot file stream, usually because the file is truncated or was not written in the expected encoded format. Callers such as decodeBytes, readMetadata, and the export flow abort reading the snapshot when this fires.

Source

Thrown at common/ledger/snapshot/file.go:178

	return string(b), err
}

// DecodeBytes reads and decodes bytes
func (r *FileReader) DecodeBytes() ([]byte, error) {
	b, err := r.decodeBytes()
	if err != nil {
		return nil, err
	}
	c := make([]byte, len(b))
	copy(c, b)
	return c, nil
}

// DecodeUVarInt reads and decodes a number
func (r *FileReader) DecodeUVarInt() (uint64, error) {
	u, err := binary.ReadUvarint(r.bufReader)
	if err != nil {
		return 0, errors.Wrapf(err, "error while reading from snapshot file: %s", r.file.Name())
	}
	return u, nil
}

// DecodeProtoMessage reads and decodes a protoMessage
func (r *FileReader) DecodeProtoMessage(m proto.Message) error {
	b, err := r.decodeBytes()
	if err != nil {
		return err
	}
	return proto.Unmarshal(b, m)
}

// Close closes the file
func (r *FileReader) Close() error {
	if r == nil {
		return nil
	}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Verify the snapshot file exists, is non-empty, and is fully written (compare size/checksum if available).
2. Re-export or regenerate the snapshot file from the source ledger.
3. Check that the file was written by a compatible version of the snapshot writer.
4. Inspect the wrapped cause (errors.Unwrap / %v of the error) to distinguish io.EOF from ErrCorrupt varint data.

Example fix

// before
u, err := reader.DecodeUVarInt()
if err != nil { return err }
// after
u, err := reader.DecodeUVarInt()
if err != nil {
  if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
    return fmt.Errorf("snapshot file truncated or incomplete: %w", err)
  }
  return err
}

fi, err := os.Stat(path)
if err != nil || fi.Size() == 0 { return fmt.Errorf("snapshot file %s missing or empty", path) }

func isSnapshotReadErr(err error) bool {
  return err != nil && strings.Contains(err.Error(), "error while reading from snapshot file")
}

u, err := reader.DecodeUVarInt()
if err != nil {
  if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
    return fmt.Errorf("truncated snapshot: %w", err)
  }
  return err
}

When it happens

Trigger: Calling DecodeUVarInt on a FileReader whose underlying file is empty, truncated, or whose byte stream is not a valid uvarint (e.g. reading a file produced by a different writer/version, or seeking to a wrong offset).

Common situations: Partial snapshot file from a crashed export; opening a snapshot file written by an incompatible Fabric version; reading past the end of the metadata section due to a corrupted length prefix.

Related errors

• internal leveldb error while iterating for txids
• error peeking [%d] bytes from block file
• error discarding [%d] bytes
• error reading [%d] bytes from file number [%d]
• dir %s not empty

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/8ab0807cfa886a0b. Report an issue: GitHub.