What causes "failed to commit private data" in hyperledger/fabric?

Inspect the wrapped (cause) error in the log line to find the actual commit failure reason.

failed to commit private data

Error message

failed to commit private data

What it means

The Reconciler pulls missing private data for old blocks from other peers and commits it via CommitPvtDataOfOldBlocks. This error wraps any failure returned by that ledger commit call during reconciliation, so the underlying cause is always in the wrapped error (e.g. hashing mismatch, ledger write failure, collection config unavailable). Reconciliation for that pass is aborted and retried on the next reconciliation interval.

Source

Thrown at gossip/privdata/reconcile.go:170

				r.logger.Debug("Reconciliation cycle finished successfully. no items to reconcile")
			}
			return nil
		}

		r.logger.Debug("got from ledger", len(missingPvtDataInfo), "blocks with missing private data, trying to reconcile...")

		dig2collectionCfg, minB, maxB := r.getDig2CollectionConfig(missingPvtDataInfo)
		fetchedData, err := r.FetchReconciledItems(dig2collectionCfg)
		if err != nil {
			r.logger.Error("reconciliation error when trying to fetch missing items from different peers:", err)
			return err
		}

		pvtDataToCommit := r.preparePvtDataToCommit(fetchedData.AvailableElements)
		unreconciled := constructUnreconciledMissingData(dig2collectionCfg, fetchedData.AvailableElements)
		pvtdataHashMismatch, err := r.CommitPvtDataOfOldBlocks(pvtDataToCommit, unreconciled)
		if err != nil {
			return errors.Wrap(err, "failed to commit private data")
		}
		r.logMismatched(pvtdataHashMismatch)
		if minB < minBlock {
			minBlock = minB
		}
		if maxB > maxBlock {
			maxBlock = maxB
		}
		totalReconciled += len(fetchedData.AvailableElements)
	}
}

func (r *Reconciler) reportReconciliationDuration(startTime time.Time) {
	r.metrics.ReconciliationDuration.With("channel", r.channel).Observe(time.Since(startTime).Seconds())
}

type collectionConfigKey struct {
	chaincodeName, collectionName string

View on GitHub (pinned to 2736b63f8f)

Solutions

Inspect the wrapped (cause) error in the log line to find the actual commit failure reason.
Check ledger/provider logs for storage errors (disk full, DB corruption) and fix the underlying storage issue.
Verify collection configurations for the affected chaincodes are consistent across the channel.
Wait for the next reconciliation cycle; reconciliation is periodic and retries failed commits automatically.
If persistent, restart the peer so the reconciler rebuilds state against a healthy ledger.

Example fix

// before (diagnose)
log.Error(err) // failed to commit private data: <cause>
// after (surface cause explicitly)
if err != nil {
    log.Errorf("failed to commit private data: %+v", errors.Unwrap(err))
}

Defensive patterns

Strategy: try-catch

Validate before calling

// before triggering reconciliation commit, verify ledger is reachable
if retriever, err := r.GetConfigHistoryRetriever(); err != nil {
    log.Warningf("ledger not ready, skipping reconcile: %v", err)
    return
}

Try / catch

pvtDataToCommit := r.preparePvtDataToCommit(fetchedData.AvailableElements)
_, err := r.CommitPvtDataOfOldBlocks(pvtDataToCommit, unreconciled)
if err != nil {
    log.Warningf("reconcile commit failed, will retry next cycle: %v", err)
    return // reconciliation retries periodically
}

Prevention

Always log the wrapped cause of this error, not just the wrapper message.
Monitor ledger storage health (disk space, DB errors) on peers with private data enabled.
Keep collection configs consistent across channel members.
Rely on periodic reconciliation retries instead of aborting on first failure.

When it happens

Trigger: Calling Reconciler.run() -> reconcile() when preparePvtDataToCommit produces fetched private data and r.CommitPvtDataOfOldBlocks(pvtDataToCommit, unreconciled) returns a non-nil error.

Common situations: Ledger backend (LevelDB/CouchDB) write errors, invalid or mismatched collection configs discovered during commit, transient ledger unavailability during channel updates, or a bug producing rwsets that fail validation when written to the transient/private data store.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/21404cf3e10456bb. Report an issue: GitHub.