hyperledger/fabric · error

error reading block file for offset %d and length %d

Error message

error reading block file for offset %d and length %d

What it means

blockfileReader.read wraps errors from file.ReadAt(b, offset): any failure reading `length` bytes at `offset` from an open block file. Beyond ordinary IO errors, ReadAt returns io.EOF when the requested range extends past end-of-file, so this error also indicates a truncated or corrupt block file.

Source

Thrown at common/ledger/blkstorage/blockfile_rw.go:83

// //  READER ////
type blockfileReader struct {
	file *os.File
}

func newBlockfileReader(filePath string) (*blockfileReader, error) {
	file, err := os.OpenFile(filePath, os.O_RDONLY, 0o600)
	if err != nil {
		return nil, errors.Wrapf(err, "error opening block file reader for file %s", filePath)
	}
	reader := &blockfileReader{file}
	return reader, nil
}

func (r *blockfileReader) read(offset int, length int) ([]byte, error) {
	b := make([]byte, length)
	_, err := r.file.ReadAt(b, int64(offset))
	if err != nil {
		return nil, errors.Wrapf(err, "error reading block file for offset %d and length %d", offset, length)
	}
	return b, nil
}

func (r *blockfileReader) close() error {
	return errors.WithStack(r.file.Close())
}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Check the wrapped cause: io.EOF/'EOF' means the file is shorter than the index expects (truncation/corruption); EIO points to hardware/storage trouble.
2. Verify blockfile size against expectations (ls -l); a truncated file means restore ledgersData from a backup taken while the peer was stopped.
3. Rebuild the ledger: remove the affected channel's data and re-join/re-sync from orderers, or restore from a snapshot.
4. Check storage health (dmesg, smartctl) if EIO errors recur before re-provisioning the peer.

Example fix

// before: querying block whose file was truncated by disk-full crash
// ERROR: error reading block file for offset 104857600 and length 329: EOF
// after (shell): restore full backup then restart
systemctl stop peer
rsync -a /backup/ledgersData/chains/chains/mychannel/ /var/hyperledger/production/ledgersData/chains/chains/mychannel/
systemctl start peer

// Go: sanity-check offset+length against file size before deep reads
func rangeValid(path string, offset, length int) error {
	st, err := os.Stat(path)
	if err != nil {
		return err
	}
	if int64(offset+length) > st.Size() {
		return fmt.Errorf("requested range [%d,%d) exceeds file size %d", offset, offset+length, st.Size())
	}
	return nil
}

// Go: treat EOF as corruption and fall back to resync, retry other IO errors
b, err := reader.read(offset, length)
if err != nil {
	if err == io.EOF || errors.Cause(err) == io.EOF {
		// truncated/corrupt blockfile: trigger ledger restore or resync from peers
	} else if isRetryableIO(errors.Cause(err)) {
		// brief backoff and retry
	}
	return err
}

When it happens

Trigger: fetchRawBytes/read resolving an index pointer (fileLocPointer) whose offset+length exceeds the actual file size, or a low-level read failure (EBADF, EIO) on the open file descriptor.

Common situations: Truncated blockfile after a crash or disk-full during write; corrupted index entries pointing past EOF; ledger files manually edited or partially restored from backup; failing disk returning IO errors.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• error opening block file writer for file %s
• error opening block file reader for file %s
• failed writing file %s: %v
• error writing config update to output
• error decoding the block number

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/b1d4b995e75f2a77. Report an issue: GitHub.