hyperledger/fabric · error

proto: Marshal called with nil

Error message

proto: Marshal called with nil

What it means

After fetching, the command sanity-checks that the delivered block is non-nil before proto.Marshal. A nil block would make the protobuf marshal panic ('proto: Marshal called with nil'), so fetch returns this error defensively when the deliver client returned success but no block.

Source

Thrown at internal/peer/channel/fetch.go:97

		lc, err2 := protoutil.GetLastConfigIndexFromBlock(iBlock)
		if err2 != nil {
			return err2
		}
		logger.Infof("Retrieving last config block: %d", lc)
		block, err = cf.DeliverClient.GetSpecifiedBlock(lc)
	default:
		num, err2 := strconv.Atoi(args[0])
		if err2 != nil {
			return fmt.Errorf("fetch target illegal: %s", args[0])
		}
		block, err = cf.DeliverClient.GetSpecifiedBlock(uint64(num))
	}
	if err != nil {
		return err
	}

	if block == nil {
		return errors.New("proto: Marshal called with nil")
	}
	b, err := proto.Marshal(block)
	if err != nil {
		return err
	}

	var file string
	if len(args) == 1 {
		file = channelID + "_" + args[0] + ".block"
	} else {
		file = args[1]
	}

	if err = os.WriteFile(file, b, 0o644); err != nil {
		return err
	}

	return nil

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Retry the fetch; transient deliver issues often resolve.
2. Check orderer logs for errors serving the requested block.
3. Verify connectivity to the orderer without intermediaries (bypass proxies).
4. If persistent, ensure orderer and peer versions are compatible.

Example fix

// not applicable — defensive internal check; fix is operational (retry/repair orderer connectivity)

// pre-check channel exists and orderer is healthy
peer channel list
curl -s --cacert ca.pem https://orderer.example.com:7050/healthz 2>/dev/null || echo 'check orderer health endpoint'

if err := cmd.Execute(); err != nil {
    if strings.Contains(err.Error(), "proto: Marshal called with nil") {
        // nil block from deliver; retry fetch, inspect orderer logs
    }
}

When it happens

Trigger: Deliver client returns no error but a nil block — e.g. a malformed/edge-case response from the orderer or an unexpected empty stream after GetSpecifiedBlock/GetNewestBlock.

Common situations: Orderer misbehaving or returning an empty response; proxy/load-balancer truncating the deliver stream; bugs in custom deliver implementations; race where the channel was deleted or reset.

Related errors

• response error: unknown type %T
• error unmarshalling
• error encoding output
• error unmarshalling original config
• error unmarshalling updated config

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/f6cf7535673a0305. Report an issue: GitHub.