hyperledger/fabric · error

error getting next element out of private data iterator, nam

Error message

error getting next element out of private data iterator, namespace <%s>, collection name <%s>, txID <%s>, due to <%s>

What it means

While iterating results from the transient store, it.Next() can fail (iterator corruption, store mutation/close mid-iteration). The retriever aborts and reports the namespace, collection, txID and wrapped cause. This happens after the iterator was created successfully, so it indicates a mid-iteration storage failure.

Source

Thrown at gossip/privdata/dataretriever.go:186

	}

	return results, nil
}

func (dr *dataRetriever) fromTransientStore(dig *protosgossip.PvtDataDigest, filter map[string]ledger.PvtCollFilter) (*util.PrivateRWSetWithConfig, error) {
	results := &util.PrivateRWSetWithConfig{}
	it, err := dr.store.GetTxPvtRWSetByTxid(dig.TxId, filter)
	if err != nil {
		return nil, errors.Errorf("was not able to retrieve private data from transient store, namespace <%s>"+
			", collection name %s, txID <%s>, due to <%s>", dig.Namespace, dig.Collection, dig.TxId, err)
	}
	defer it.Close()

	maxEndorsedAt := uint64(0)
	for {
		res, err := it.Next()
		if err != nil {
			return nil, errors.Errorf("error getting next element out of private data iterator, namespace <%s>"+
				", collection name <%s>, txID <%s>, due to <%s>", dig.Namespace, dig.Collection, dig.TxId, err)
		}
		if res == nil {
			return results, nil
		}
		rws := res.PvtSimulationResultsWithConfig
		if rws == nil {
			dr.logger.Debug("Skipping nil PvtSimulationResultsWithConfig received at block height", res.ReceivedAtBlockHeight)
			continue
		}
		txPvtRWSet := rws.PvtRwset
		if txPvtRWSet == nil {
			dr.logger.Debug("Skipping empty PvtRwset of PvtSimulationResultsWithConfig received at block height", res.ReceivedAtBlockHeight)
			continue
		}

		colConfigs, found := rws.CollectionConfigs[dig.Namespace]
		if !found {

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Retry the pull once gossip/the peer is idle — shutdown races are transient.
2. Restart the peer to recreate leveldb iterators over a clean state.
3. Check disk health and transient store directory integrity.
4. If corruption persists, rebuild peer DBs and re-fetch pvt data from other peers.

Example fix

// before
res, err := it.Next()
if err != nil {
    return nil, errors.Errorf("error getting next element ...")
}

// after: safe iteration with close before retry
res, err := it.Next()
if err != nil {
    logger.Warningf("iterator failed for %s: %v", dig.TxId, err)
    it.Close()
    return nil, nil // allow gossip pull retry
}

it, err := store.GetTxPvtRWSetByTxid(txid, filter)
if err != nil {
    return err
}
defer it.Close() // close before any retry to avoid iterator leaks

func iteratorExhausted(it ledger.ResultsIterator) (bool, error) {
    res, err := it.Next()
    if err != nil {
        return false, err
    }
    return res == nil, nil
}

res, err := it.Next()
if err != nil {
    it.Close()
    logger.Warningf("iterator error for %s (%v); retrying pull", dig.TxId, err)
    scheduleRetry()
    return
}

When it happens

Trigger: it.Next() returns a non-nil error while paging through the private-data iterator — concurrent store close/shutdown, leveldb iterator failure, or corrupted pvt simulation records.

Common situations: Peer shutdown racing an in-flight gossip pull; an unclean crash leaving leveldb in a state where iterators fail; transient store files on failing storage.

Related errors

• was not able to retrieve private data from transient store,
• query iterator not found
• only applicable for private data
• collection-name: %s -- cannot unmarshal identity bytes into
• collection-name: %s -- collection member '%s' is not part of

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/e90b7404e30e5774. Report an issue: GitHub.