hyperledger/fabric · error

empty block or block header, channel: %s

Error message

empty block or block header, channel: %s

What it means

SyncBuffer.HandleBlock forwards blocks fetched from remote orderers into an internal channel for the next processing stage. If the fetched block is nil or lacks a Header, it is unusable and this error is returned instead of enqueueing garbage downstream.

Source

Thrown at orderer/consensus/smartbft/sync_buffer.go:35

	blockCh  chan *common.Block
	stopCh   chan struct{}
	stopOnce sync.Once
}

func NewSyncBuffer(capacity uint) *SyncBuffer {
	if capacity == 0 {
		capacity = 10
	}
	return &SyncBuffer{
		blockCh: make(chan *common.Block, capacity),
		stopCh:  make(chan struct{}),
	}
}

// HandleBlock gives the block to the next stage of processing after fetching it from a remote orderer.
func (sb *SyncBuffer) HandleBlock(channelID string, block *common.Block) error {
	if block == nil || block.Header == nil {
		return errors.Errorf("empty block or block header, channel: %s", channelID)
	}

	select {
	case sb.blockCh <- block:
		return nil
	case <-sb.stopCh:
		return errors.Errorf("SyncBuffer stopping, channel: %s", channelID)
	}
}

func (sb *SyncBuffer) PullBlock(seq uint64) *common.Block {
	var block *common.Block
	for {
		select {
		case block = <-sb.blockCh:
			if block == nil || block.Header == nil {
				return nil
			}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Verify BlockPuller endpoint configuration (TLS certs, endpoints, ports) points at healthy orderers of the channel.
2. Remove/unhealthy endpoints: prune HeightsByEndpoints targets that return bad data and re-sync from a good consenter.
3. Check the remote orderer's ledger health at the requested height; repair or re-join it if its ledger is corrupted.
4. Retry synchronization — transient bad responses from one endpoint are typically bypassed on the next attempt.

Example fix

// before
// endpoints include a stale node returning empty blocks
LocalConfigCluster.SendBufferSize = 10 // endpoints unchanged

// after
// remove stale endpoints from cluster.* config and restart orderer
// cluster.replication.endpoints = [healthy-orderer1:7050, healthy-orderer2:7050]

func safeHandleBlock(sb *SyncBuffer, channelID string, b *common.Block) error {
    if b == nil || b.Header == nil {
        return fmt.Errorf("skip nil/headerless block on %s", channelID)
    }
    return sb.HandleBlock(channelID, b)
}

func isUsableBlock(b *common.Block) bool {
    return b != nil && b.Header != nil
}

err := sb.HandleBlock(channelID, block)
if err != nil && strings.Contains(err.Error(), "empty block or block header") {
    // remote endpoint returned garbage: drop endpoint and retry sync
    return retrySyncWithoutEndpoint(badEndpoint)
}

When it happens

Trigger: The block puller delivers a nil block or a headerless block from a remote orderer during synchronization — e.g. a remote endpoint returning an empty/garbage response for the requested sequence.

Common situations: A misbehaving or misconfigured remote orderer endpoint (wrong port, a non-orderer service) returning malformed blocks; a puller hitting an endpoint whose ledger is empty or corrupted; race where a stopped/starting node returns empty results.

Related errors

• cannot get create BlockPuller
• SyncBuffer stopping, channel: %s
• consenter options type mismatch
• failed to unmarshal BFT metadata configuration
• invalid BFT metadata configuration

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/b57579721c186f6d. Report an issue: GitHub.