hyperledger/fabric · error

error unmarshalling Proposal

Error message

error unmarshalling Proposal

What it means

Returned by protoutil.UnmarshalProposal when proto.Unmarshal cannot decode bytes into a peer.Proposal message. The wrapper names the failing message type. It means the proposal bytes (typically ProposalBytes from a SignedProposal) are invalid, truncated, or of another message type.

Source

Thrown at protoutil/unmarshalers.go:151

// UnmarshalChaincodeEvents unmarshals bytes to a ChaincodeEvent
func UnmarshalChaincodeEvents(eBytes []byte) (*peer.ChaincodeEvent, error) {
	chaincodeEvent := &peer.ChaincodeEvent{}
	err := proto.Unmarshal(eBytes, chaincodeEvent)
	return chaincodeEvent, errors.Wrap(err, "error unmarshalling ChaicnodeEvent")
}

// UnmarshalProposalResponsePayload unmarshals bytes to a ProposalResponsePayload
func UnmarshalProposalResponsePayload(prpBytes []byte) (*peer.ProposalResponsePayload, error) {
	prp := &peer.ProposalResponsePayload{}
	err := proto.Unmarshal(prpBytes, prp)
	return prp, errors.Wrap(err, "error unmarshalling ProposalResponsePayload")
}

// UnmarshalProposal unmarshals bytes to a Proposal
func UnmarshalProposal(propBytes []byte) (*peer.Proposal, error) {
	prop := &peer.Proposal{}
	err := proto.Unmarshal(propBytes, prop)
	return prop, errors.Wrap(err, "error unmarshalling Proposal")
}

// UnmarshalTransaction unmarshals bytes to a Transaction
func UnmarshalTransaction(txBytes []byte) (*peer.Transaction, error) {
	tx := &peer.Transaction{}
	err := proto.Unmarshal(txBytes, tx)
	return tx, errors.Wrap(err, "error unmarshalling Transaction")
}

// UnmarshalChaincodeActionPayload unmarshals bytes to a ChaincodeActionPayload
func UnmarshalChaincodeActionPayload(capBytes []byte) (*peer.ChaincodeActionPayload, error) {
	cap := &peer.ChaincodeActionPayload{}
	err := proto.Unmarshal(capBytes, cap)
	return cap, errors.Wrap(err, "error unmarshalling ChaincodeActionPayload")
}

// UnmarshalChaincodeProposalPayload unmarshals bytes to a ChaincodeProposalPayload
func UnmarshalChaincodeProposalPayload(bytes []byte) (*peer.ChaincodeProposalPayload, error) {

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Verify the client marshals peer.Proposal into SignedProposal.ProposalBytes (via protoutil.MarshalOrPanic / CreateProposal) before signing.
2. Confirm len(propBytes) > 0 and that signature verification passes before unmarshaling.
3. Align SDK and peer Fabric versions so the Proposal schema matches.
4. Check that the bytes are the proposal itself, not the signature or header slice.
5. Reject the request with a descriptive error (Bad Request) so clients can fix their submission.

Example fix

// before
prop, _ := protoutil.UnmarshalProposal(signedProp.Signature) // signature bytes, wrong field
// after
prop, err := protoutil.UnmarshalProposal(signedProp.ProposalBytes)
if err != nil {
    return status.Errorf(codes.InvalidArgument, "malformed proposal: %v", err)
}

func validSignedProposal(sp *peer.SignedProposal) bool {
    return sp != nil && len(sp.ProposalBytes) > 0 && len(sp.Signature) > 0
}

func isProposal(v any) bool {
    _, ok := v.(*peer.Proposal)
    return ok
}

prop, err := protoutil.UnmarshalProposal(sp.ProposalBytes)
if err != nil {
    return status.Errorf(codes.InvalidArgument, "malformed proposal: %v", err)
}

When it happens

Trigger: Calling UnmarshalProposal on SignedProposal.ProposalBytes that are empty or corrupted, on bytes of a different message (e.g. a Header), or proposals built by an SDK with mismatched protobuf definitions; reached from CheckACL, getSignedData, UnpackProposal, validateProposal, and CheckPolicy.

Common situations: Custom proposal submitter sending malformed SignedProposals (bad gRPC framing, byte-slice copies); peer-side ACL/policy validation of client requests; version drift between fabric-sdk-node/go and peer.

Understand the failure class

Background: "cannot parse invalid wire-format data", "cannot unmarshal", "failed unmarshalling": protobuf unmarshal errors explained — this error's family across 10 libraries.

Related errors

• error unmarshalling ChaincodeHeaderExtension
• error unmarshalling ChaincodeProposalPayload
• error unmarshalling
• error unmarshalling original config
• error unmarshalling updated config

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/404aa86f3db925a5. Report an issue: GitHub.