hyperledger/fabric · error

last block header hash is missing

Error message

last block header hash is missing

What it means

NewBlockVerificationAssistantFromConfig requires the hash of the last delivered block's header to seed chain verification of subsequent blocks. An empty lastBlockHeaderHash means the assistant could not anchor the next block's PreviousHash check, so construction fails immediately.

Source

Thrown at common/deliverclient/block_verification.go:161

		configBlockHeader:   configBlock.Header,
		lastBlockHeader:     lastBlock.Header,
		lastBlockHeaderHash: protoutil.BlockHeaderHash(lastBlock.Header),
		logger:              lg,
	}

	return a, nil
}

// NewBlockVerificationAssistantFromConfig creates a new BlockVerificationAssistant from a common.Config.
// This is used in the peer, since when the peer starts from a snapshot we may not have access to the last config-block,
// only to the config object.
func NewBlockVerificationAssistantFromConfig(config *common.Config, lastBlockNumber uint64, lastBlockHeaderHash []byte, channelID string, cryptoProvider bccsp.BCCSP, lg *flogging.FabricLogger) (*BlockVerificationAssistant, error) {
	if config == nil {
		return nil, errors.Errorf("config is nil")
	}

	if len(lastBlockHeaderHash) == 0 {
		return nil, errors.Errorf("last block header hash is missing")
	}

	bva := &BlockVerifierAssembler{
		Logger: lg,
		BCCSP:  cryptoProvider,
	}
	verifierFunc, err := bva.VerifierFromConfig(&common.ConfigEnvelope{Config: config}, channelID)
	if err != nil {
		return nil, errors.WithMessage(err, "error creating verifier function")
	}

	a := &BlockVerificationAssistant{
		channelID:           channelID,
		verifierAssembler:   bva,
		sigVerifierFunc:     verifierFunc,
		lastBlockHeader:     &common.BlockHeader{Number: lastBlockNumber},
		lastBlockHeaderHash: lastBlockHeaderHash,
		logger:              lg,

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Fetch the channel's last block (e.g. via OrdererClient SendReceive / query ledger height) and compute lastBlockHeaderHash = protoutil.BlockHeaderHash(lastBlock.Header).
2. For a fresh ledger, start from the genesis block and pass protoutil.BlockHeaderHash(genesisBlock.Header).
3. Guard the call site: skip or correct the call when the cached last block is nil.

Example fix

// before
bva, err := NewBlockVerificationAssistantFromConfig(config, lastNum, nil, chID, bccsp, lg)

// after
if lastBlock == nil || lastBlock.Header == nil { return errors.New("no last block available") }
lastHash := protoutil.BlockHeaderHash(lastBlock.Header)
bva, err := NewBlockVerificationAssistantFromConfig(config, lastNum, lastHash, chID, bccsp, lg)

if len(lastBlockHeaderHash) == 0 {
    last, err := fetchLastBlock(ordererClient, channelID)
    if err != nil { return err }
    lastBlockHeaderHash = protoutil.BlockHeaderHash(last.Header)
}
bva, err := NewBlockVerificationAssistantFromConfig(config, lastNum, lastBlockHeaderHash, channelID, bccsp, lg)

func hasLastHeaderHash(h []byte) bool { return len(h) > 0 }

bva, err := NewBlockVerificationAssistantFromConfig(cfg, num, hash, chID, bccsp, lg)
if err != nil {
    if strings.Contains(err.Error(), "last block header hash is missing") {
        // fetch last block and retry once
    }
    return err
}

When it happens

Trigger: Calling NewBlockVerificationAssistantFromConfig (directly or via a deliver client factory) with a nil/empty lastBlockHeaderHash argument — typically when a caller computed the last header hash from a nil/zero last block, or passed an unset variable.

Common situations: Custom block-replay/verification tools calling the constructor on a fresh channel without first fetching the genesis block header hash; wiring the deliver client before any block was cached.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• missing channel header
• config block channel ID [%s] does not match expected: [%s]
• failed to verify transactions are well formed for block with
• Header.DataHash is different from Hash(block.Data) for block
• block with id [%d] on channel [%s] does not have metadata or

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/887988f2076a3d99. Report an issue: GitHub.