What causes "error seeking block file [%s] to startOffset [%d]" in hyperledger/fabric?

Inspect the wrapped OS error (%v) to identify EINVAL/EBADF/EIO and address the root cause

error seeking block file [%s] to startOffset [%d]

Error message

error seeking block file [%s] to startOffset [%d]

What it means

Wraps the error returned by file.Seek when newBlockfileStream fails to position the blockfile reader at the requested startOffset. This indicates an OS-level seek failure (bad descriptor, I/O error, or negative/invalid offset), not merely a wrong position. If the seek succeeds but lands elsewhere, a panic is raised instead (error 243).

Source

Thrown at common/ledger/blkstorage/block_stream.go:64

	fileNum          int
	blockStartOffset int64
	blockBytesOffset int64
}

// /////////////////////////////////
// blockfileStream functions
// //////////////////////////////////
func newBlockfileStream(rootDir string, fileNum int, startOffset int64) (*blockfileStream, error) {
	filePath := deriveBlockfilePath(rootDir, fileNum)
	logger.Debugf("newBlockfileStream(): filePath=[%s], startOffset=[%d]", filePath, startOffset)
	var file *os.File
	var err error
	if file, err = os.OpenFile(filePath, os.O_RDONLY, 0o600); err != nil {
		return nil, errors.Wrapf(err, "error opening block file %s", filePath)
	}
	var newPosition int64
	if newPosition, err = file.Seek(startOffset, 0); err != nil {
		return nil, errors.Wrapf(err, "error seeking block file [%s] to startOffset [%d]", filePath, startOffset)
	}
	if newPosition != startOffset {
		panic(fmt.Sprintf("Could not seek block file [%s] to startOffset [%d]. New position = [%d]",
			filePath, startOffset, newPosition))
	}
	s := &blockfileStream{fileNum, file, bufio.NewReader(file), startOffset}
	return s, nil
}

func (s *blockfileStream) nextBlockBytes() ([]byte, error) {
	blockBytes, _, err := s.nextBlockBytesAndPlacementInfo()
	return blockBytes, err
}

// nextBlockBytesAndPlacementInfo returns bytes for the next block
// along with the offset information in the block file.
// An error `ErrUnexpectedEndOfBlockfile` is returned if a partial written data is detected
// which is possible towards the tail of the file if a crash had taken place during appending of a block

View on GitHub (pinned to 2736b63f8f)

Solutions

Inspect the wrapped OS error (%v) to identify EINVAL/EBADF/EIO and address the root cause
Verify the offset source (checkpoint file, blockfilesInfo, or caller-supplied startOffset) is not corrupt
Rebuild ledger state via peer rollback/rebuild or restore from a snapshot if offsets are corrupt
Check storage health (dmesg, SMART) if EIO is reported

Defensive patterns

Strategy: validation

Validate before calling

if startOffset < 0 {
    return fmt.Errorf("invalid startOffset %d for file %d", startOffset, fileNum)
}

Try / catch

s, err := newBlockfileStream(rootDir, num, offset)
if err != nil {
    logger.Errorf("seek failed on blockfile %d@%d: %v", num, offset, err)
    return err
}

Prevention

Validate offsets stored in checkpoint/index metadata before use
Keep ledger files on healthy local storage; monitor for EIO
Do not modify ledger files externally while the peer runs

When it happens

Trigger: newBlockfileStream(rootDir, fileNum, startOffset) where file.Seek(startOffset, 0) returns an error — e.g. startOffset is negative, the file descriptor is bad, or an underlying I/O error occurs.

Common situations: Corrupt checkpoint/index metadata storing a negative or garbage offset; ledger files replaced underneath a running process; disks with failing sectors returning EIO during seek on some filesystems.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/6dbe4965e90c613f. Report an issue: GitHub.