hyperledger/fabric · error

error marshaling proposal

Error message

error marshaling proposal

What it means

After the proposal is signed, the bytes must be serialized with proto.Marshal. If protobuf marshaling of the *pb.Proposal fails, the error is wrapped as "error marshaling proposal". This signals the proposal message is corrupt or violates protobuf invariants (e.g. invalid oneof state, unsupported field).

Source

Thrown at internal/peer/lifecycle/chaincode/common.go:59

// Writer defines the interface needed for writing a file
type Writer interface {
	WriteFile(string, string, []byte) error
}

func signProposal(proposal *pb.Proposal, signer Signer) (*pb.SignedProposal, error) {
	// check for nil argument
	if proposal == nil {
		return nil, errors.New("proposal cannot be nil")
	}

	if signer == nil {
		return nil, errors.New("signer cannot be nil")
	}

	proposalBytes, err := proto.Marshal(proposal)
	if err != nil {
		return nil, errors.Wrap(err, "error marshaling proposal")
	}

	signature, err := signer.Sign(proposalBytes)
	if err != nil {
		return nil, err
	}

	return &pb.SignedProposal{
		ProposalBytes: proposalBytes,
		Signature:     signature,
	}, nil
}

func createPolicyBytes(signaturePolicy, channelConfigPolicy string) ([]byte, error) {
	if signaturePolicy == "" && channelConfigPolicy == "" {
		// no policy, no problem
		return nil, nil
	}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Inspect the wrapped underlying error to identify which field fails marshaling
2. Rebuild the proposal via the standard createInput/createCommand path instead of hand-crafting it
3. Align protobuf/fabric dependency versions in go.mod

Example fix

// before
sp, err := signProposal(customProposal, signer) // corrupt proposal
// after
proposal, err := createInput(...).buildProposal() // canonical construction
if err != nil {
    return err
}
sp, err := signProposal(proposal, signer)

sp, err := signProposal(proposal, signer)
if err != nil {
    if strings.Contains(err.Error(), "error marshaling proposal") {
        return fmt.Errorf("proposal bytes invalid: %w", errors.Unwrap(err))
    }
    return err
}

When it happens

Trigger: signProposal calls proto.Marshal(proposal) and receives a non-nil error — typically from a hand-crafted or corrupted pb.Proposal rather than one built by the CLI.

Common situations: Custom clients constructing proposals with invalid fields; protobuf version mismatch in vendored builds; fuzz/edge tests injecting malformed messages.

Related errors

• proto: Marshal called with nil
• unsupported pointer type %v for field %s (must be proto)
• could not marshal field %s
• failed to marshal args
• error marshaling

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/e94f404d8a52d792. Report an issue: GitHub.