internal leveldb error while retrieving data from db iterato

Error message

internal leveldb error while retrieving data from db iterator

What it means

During deleteAll, the code iterates over all keys in a handle's namespace to build a delete batch. If the underlying LevelDB iterator reports an error mid-iteration (dbIter.Error() after Next()), the delete is aborted and this wrapped error is returned. It indicates the scan itself failed, so data was NOT fully deleted.

Source

Thrown at common/ledger/util/leveldbhelper/leveldb_provider.go:231

func (h *DBHandle) deleteAll() error {
	iter, err := h.GetIterator(nil, nil)
	if err != nil {
		return err
	}
	defer iter.Release()

	// use leveldb iterator directly to be more efficient
	dbIter := iter.Iterator

	// This is common code shared by all the leveldb instances. Because each leveldb has its own key size pattern,
	// each batch is limited by memory usage instead of number of keys. Once the batch memory usage reaches maxBatchSize,
	// the batch will be committed.
	numKeys := 0
	batchSize := 0
	batch := &leveldb.Batch{}
	for dbIter.Next() {
		if err := dbIter.Error(); err != nil {
			return errors.Wrap(err, "internal leveldb error while retrieving data from db iterator")
		}
		key := dbIter.Key()
		numKeys++
		batchSize = batchSize + len(key)
		batch.Delete(key)
		if batchSize >= maxBatchSize {
			if err := h.db.WriteBatch(batch, true); err != nil {
				return err
			}
			logger.Infof("Have removed %d entries for channel %s in leveldb %s", numKeys, h.dbName, h.db.conf.DBPath)
			batchSize = 0
			batch.Reset()
		}
	}
	if batch.Len() > 0 {
		return h.db.WriteBatch(batch, true)
	}
	return nil

View on GitHub (pinned to 2736b63f8f)

Solutions

Read the wrapped LevelDB cause in the error chain and fix it (missing/corrupt files, I/O errors)
Stop the process, back up the DB directory, and attempt leveldb recovery or restore from snapshot/backup
Check disk space and filesystem health (dmesg, SMART) before retrying deletion
If corruption is unrecoverable, recreate the ledger data directory and resync from peers/snapshot

Example fix

// before
err := dbHandle.DeleteAll() // returns wrapped iterator error
// after: inspect cause and recover
if err := dbHandle.DeleteAll(); err != nil {
	log.Errorf("deleteAll failed: %v", errors.Unwrap(err))
	// restore from backup or resync before retrying
}

Defensive patterns

Strategy: try-catch

Validate before calling

if _, err := os.Stat(dbPath); err != nil { return fmt.Errorf("db path missing: %w", err) }
if err := checkDiskSpace(dbPath, minFree); err != nil { return err }

Type guard

func isLevelDBIteratorError(err error) bool {
	return err != nil && strings.Contains(err.Error(), "internal leveldb error while retrieving data")
}

Try / catch

err := handle.DeleteAll()
var wrapped error
if errors.As(err, &wrapped) {
	cause := errors.Unwrap(err)
	log.Errorf("underlying leveldb failure: %v", cause)
	// trigger backup/restore or resync path
}

Prevention

Monitor disk space and I/O health on ledger volumes
Back up ledger directories before delete/close operations
Avoid killing the process during compaction/writes to prevent corruption
Surface errors.Unwrap(err) in logs to identify the root leveldb cause

When it happens

Trigger: Calling DeleteAll/Close on a DBHandle while the internal iterator hits a LevelDB read error — corrupted SST files, missing MANIFEST, I/O failure during compaction/scan, or a snapshot inconsistency. Any dbIter.Next() followed by a non-nil dbIter.Error() in deleteAll produces it.

Common situations: Corrupted ledger database after unclean shutdown or disk-full during writes; hardware/IO errors while the node deletes a namespace's data; version/file-lock issues leaving the DB in a bad state during cleanup at shutdown.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/601a7b71e1f3ccb3. Report an issue: GitHub.