hyperledger/fabric · error

error while writing data format to the snapshot file: %s

Error message

error while writing data format to the snapshot file: %s

What it means

Returned by snapshot CreateFile when writing the one-byte data-format header to the just-created snapshot file fails. The file exists but the initial write errored (I/O failure or closed stream), so the writer cannot be returned.

Source

Thrown at common/ledger/snapshot/file.go:51

// CreateFile creates a new file for exporting the ledger snapshot data
// This function returns an error if the file already exists. The `dataformat` is the first byte
// written to the file. The function newHash is used to construct an hash.Hash for computing the hash-sum of the data stream
func CreateFile(filePath string, dataformat byte, newHashFunc NewHashFunc) (*FileWriter, error) {
	hashImpl, err := newHashFunc()
	if err != nil {
		return nil, err
	}
	// create the file only if it does not already exist.
	// set the permission mode to read-only, as once the file is closed, we do not support modifying the file
	file, err := os.OpenFile(filePath, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0o444)
	if err != nil {
		return nil, errors.Wrapf(err, "error while creating the snapshot file: %s", filePath)
	}
	bufWriter := bufio.NewWriter(file)
	multiWriter := io.MultiWriter(bufWriter, hashImpl)
	if _, err := multiWriter.Write([]byte{dataformat}); err != nil {
		file.Close()
		return nil, errors.Wrapf(err, "error while writing data format to the snapshot file: %s", filePath)
	}
	return &FileWriter{
		file:              file,
		bufWriter:         bufWriter,
		multiWriter:       multiWriter,
		hasher:            hashImpl,
		varintReusableBuf: make([]byte, binary.MaxVarintLen64),
	}, nil
}

// EncodeString encodes and appends the string to the data stream
func (c *FileWriter) EncodeString(str string) error {
	return c.EncodeBytes([]byte(str))
}

// EncodeProtoMessage encodes and appends a proto message to the data stream
func (c *FileWriter) EncodeProtoMessage(m proto.Message) error {
	if m == nil || !m.ProtoReflect().IsValid() {

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Free disk space on the snapshot volume and retry the snapshot export
2. Check the wrapped error for the OS-level write failure

When it happens

Trigger: Thrown at common/ledger/snapshot/file.go:51 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/7fc5e136f78834fd. Report an issue: GitHub.