hyperledger/fabric · error

error opening block file reader for file %s

Error message

error opening block file reader for file %s

What it means

newBlockfileReader wraps errors from os.OpenFile(filePath, O_RDONLY, 0o600) when opening an existing block file for reading. It is returned to callers like fetchRawBytes when a block/transaction is retrieved from the file-based block store. The wrapped OS error gives the actual cause.

Source

Thrown at common/ledger/blkstorage/blockfile_rw.go:73

		return err
	}
	w.file = file
	return nil
}

func (w *blockfileWriter) close() error {
	return errors.WithStack(w.file.Close())
}

// //  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. Inspect the wrapped cause: 'no such file' means the blockfile is missing; 'permission denied' means fix file ownership/mode.
  2. Restore the missing/corrupted ledger files from a known-good backup of ledgersData taken while the peer was stopped.
  3. Fix permissions: chown/chmod the blockfile and its directory so the peer process user can read them (files are 0o600).
  4. If the ledger is irrecoverable, drop the channel data (peer channel join again / remove ledgersData for that channel) and re-sync from the ordering service or a snapshot.

Example fix

// before: blockfile copied by root with restrictive perms, peer runs as 'peer'
// ERROR: error opening block file reader for file .../blockfile_000000: open ...: permission denied
// after (shell):
chown -R peer:peer /var/hyperledger/production/ledgersData
chmod -R u+rwX /var/hyperledger/production/ledgersData
Defensive patterns

Strategy: try-catch

Validate before calling

// Go: verify the block file exists and is readable before querying the ledger
func blockFileReadable(chainsDir, channel string, num uint64) error {
	p := filepath.Join(chainsDir, "chains", channel, fmt.Sprintf("blockfile_%06d", num))
	f, err := os.Open(p)
	if err != nil {
		return err
	}
	return f.Close()
}

Try / catch

// Go: distinguish missing vs permission vs other when reading via the store
block, err := store.RetrieveBlockByNumber(blkNum)
if err != nil {
	switch c := errors.Cause(err).(type) {
	case *fs.PathError:
		if os.IsNotExist(c) {
			// ledger file missing: restore from backup or resync
		}
		if os.IsPermission(c) {
			// fix ownership/mode
		}
	default:
		return err
	}
}

Prevention

When it happens

Trigger: Calling GetBlockByNumber/GetTransactionById etc. (leading to fetchRawBytes -> newBlockfileReader) when the blockfile_XXXXXX file is missing, unreadable due to permissions, or the path refers to something that is not a regular file.

Common situations: Ledger data directory partially deleted or restored from an incomplete backup; files copied between hosts with wrong ownership/permissions; block file removed while peer was down; NFS/volume mount issues; attempting to query a channel whose ledger files were pruned.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/256d9b69ae705b54. Report an issue: GitHub.