hyperledger/fabric · error

error decoding input

Error message

error decoding input

What it means

In `encodeProto` (cmd/configtxlator/main.go:143), `protolator.DeepUnmarshalJSON(input, msg)` failed to decode the JSON input file into the target proto message. The JSON either isn't valid JSON or doesn't match the schema/field types of the --type message. configtxlator wraps this as 'error decoding input'.

Source

Thrown at cmd/configtxlator/main.go:143

	fmt.Println(metadata.GetVersionInfo())
}

func encodeProto(msgName string, input, output *os.File) error {
	mt, err := protoregistry.GlobalTypes.FindMessageByName(protoreflect.FullName(msgName))
	if err != nil {
		return errors.Wrapf(err, "error encode input")
	}

	msgType := reflect.TypeOf(mt.Zero().Interface())

	if msgType == nil {
		return errors.Errorf("message of type %s unknown", msgType)
	}
	msg := reflect.New(msgType.Elem()).Interface().(proto.Message)

	err = protolator.DeepUnmarshalJSON(input, msg)
	if err != nil {
		return errors.Wrapf(err, "error decoding input")
	}

	if msg == nil {
		return errors.New("error marshaling: proto: Marshal called with nil")
	}
	out, err := proto.Marshal(msg)
	if err != nil {
		return errors.Wrapf(err, "error marshaling")
	}

	_, err = output.Write(out)
	if err != nil {
		return errors.Wrapf(err, "error writing output")
	}

	return nil
}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Validate the input file is well-formed JSON (run it through jq or a JSON linter).
2. Ensure --type matches the JSON content (e.g. common.Envelope JSON needs --type common.Envelope, not common.Config).
3. Remove unknown fields or re-export the JSON from the same Fabric version's configtxlator proto_decode.
4. Confirm you are passing the JSON file (not the .pb binary) to --input.

Example fix

// before: type mismatch
$ configtxlator proto_encode --type common.Config --input envelope.json --output out.pb
// after: match type to content
$ configtxlator proto_encode --type common.Envelope --input envelope.json --output out.pb

// Validate JSON parses and matches the expected type before encoding
import json
payload = json.load(open(input_path))
if type_arg == 'common.Envelope' and 'signature' not in payload:
    raise SystemExit('input looks like an Envelope but --type is not common.Envelope')
if type_arg == 'common.Config' and 'channel_group' not in payload:
    raise SystemExit('input does not look like common.Config')

out, err := exec.Command("configtxlator", "proto_encode", "--type", t, "--input", f, "--output", o).CombinedOutput()
if err != nil && strings.Contains(string(out), "error decoding input") {
	return fmt.Errorf("JSON in %s does not match %s; run: jq . %s", f, t, f)
}

When it happens

Trigger: Running `configtxlator proto_encode` with an input JSON that is syntactically invalid, empty, truncated, contains unknown fields (strict decoding), or whose field types don't match the --type message schema (e.g. passing an Envelope JSON while --type is common.Config).

Common situations: Hand-editing exported JSON and breaking its syntax; encoding with the wrong --type for the JSON content; exporting JSON from a different Fabric proto version; feeding a protobuf binary file instead of JSON.

Related errors

• error encode input
• message of type %s unknown
• error marshaling: proto: Marshal called with nil
• error marshaling
• error writing output

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/f97bbaff955843f0. Report an issue: GitHub.