What causes "failed to marshal chaincode event" in hyperledger/fabric?

Inspect the wrapped (cause) error to find why the event bytes failed to marshal

failed to marshal chaincode event

Error message

failed to marshal chaincode event

What it means

After successful simulation, the endorser serializes the chaincode event (CreateCCEventBytes) to embed in the proposal response. If that marshaling fails, the whole proposal processing fails with 'failed to marshal chaincode event' wrapping the underlying error.

Source

Thrown at core/endorser/endorser.go:416

		txParams.TXSimulator = txSim
		txParams.HistoryQueryExecutor = hqe
	}

	cdLedger, err := e.Support.ChaincodeEndorsementInfo(up.ChannelID(), up.ChaincodeName, txParams.TXSimulator)
	if err != nil {
		return nil, errors.WithMessagef(err, "make sure the chaincode %s has been successfully defined on channel %s and try again", up.ChaincodeName, up.ChannelID())
	}

	// 1 -- simulate
	res, simulationResult, ccevent, ccInterest, err := e.simulateProposal(txParams, up.ChaincodeName, up.Input)
	if err != nil {
		return nil, errors.WithMessage(err, "error in simulation")
	}

	cceventBytes, err := CreateCCEventBytes(ccevent)
	if err != nil {
		return nil, errors.Wrap(err, "failed to marshal chaincode event")
	}

	prpBytes, err := protoutil.GetBytesProposalResponsePayload(up.ProposalHash, res, simulationResult, cceventBytes, &pb.ChaincodeID{
		Name:    up.ChaincodeName,
		Version: cdLedger.Version,
	})
	if err != nil {
		logger.Warning("Failed marshaling the proposal response payload to bytes", err)
		return nil, errors.WithMessage(err, "failed to create the proposal response")
	}

	// if error, capture endorsement failure metric
	meterLabels := []string{
		"channel", up.ChannelID(),
		"chaincode", up.ChaincodeName,
	}

	switch {

View on GitHub (pinned to 2736b63f8f)

Solutions

Inspect the wrapped (cause) error to find why the event bytes failed to marshal
Fix the chaincode to emit a valid, reasonably sized event name/payload
Validate event payload bytes before SetEvent in chaincode

Example fix

// before
stub.SetEvent("evt", nil) // or invalid payload
// after
stub.SetEvent("evt", []byte("valid-payload"))

Defensive patterns

Strategy: try-catch

Validate before calling

if ccevent != nil && len(ccevent.Payload) > maxEventSize {
    return errors.New("chaincode event payload too large")
}

Try / catch

cceventBytes, err := CreateCCEventBytes(ccevent)
if err != nil {
    return errors.Wrap(err, "failed to marshal chaincode event")
}

Prevention

Emit small, valid event payloads from chaincode (SetEvent)
Inspect the wrapped cause with errors.Cause/Unwrap when this fires
Test event emission paths in chaincode unit tests

When it happens

Trigger: A chaincode sets a ChaincodeEvent whose payload cannot be marshaled (e.g. event produced during simulation is malformed), causing CreateCCEventBytes to return an error.

Common situations: Chaincode emitting very large or invalid event payloads; corrupted event objects from custom chaincode shim usage; binary/encoding edge cases in event payload bytes.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/87314be23197c418. Report an issue: GitHub.