error marshalling proto message to write to the snapshot fil

Error message

error marshalling proto message to write to the snapshot file: %s

What it means

This error is returned when proto.Marshal itself fails while serializing a valid proto message for the snapshot file. EncodeProtoMessage wraps the underlying proto error with the snapshot file name. Unlike error 310, the message was non-nil but its contents could not be marshalled (e.g. required extensions, unknown enum values, or marshal-time restrictions).

Source

Thrown at common/ledger/snapshot/file.go:74

		multiWriter:       multiWriter,
		hasher:            hashImpl,
		varintReusableBuf: make([]byte, binary.MaxVarintLen64),
	}, nil
}

// EncodeString encodes and appends the string to the data stream
func (c *FileWriter) EncodeString(str string) error {
	return c.EncodeBytes([]byte(str))
}

// EncodeProtoMessage encodes and appends a proto message to the data stream
func (c *FileWriter) EncodeProtoMessage(m proto.Message) error {
	if m == nil || !m.ProtoReflect().IsValid() {
		return errors.Errorf("error marshalling proto message to write to the snapshot file: %s: proto: Marshal called with nil", c.file.Name())
	}
	b, err := proto.Marshal(m)
	if err != nil {
		return errors.Wrapf(err, "error marshalling proto message to write to the snapshot file: %s", c.file.Name())
	}
	return c.EncodeBytes(b)
}

// EncodeBytes encodes and appends bytes to the data stream
func (c *FileWriter) EncodeBytes(b []byte) error {
	if err := c.EncodeUVarint(uint64(len(b))); err != nil {
		return err
	}
	if _, err := c.multiWriter.Write(b); err != nil {
		return errors.Wrapf(err, "error while writing data to the snapshot file: %s", c.file.Name())
	}
	return nil
}

// EncodeUVarint encodes and appends a number to the data stream
func (c *FileWriter) EncodeUVarint(u uint64) error {
	n := binary.PutUvarint(c.varintReusableBuf, u)

View on GitHub (pinned to 2736b63f8f)

Solutions

Inspect the wrapped inner error from proto.Marshal to identify the offending message/field
Validate/sanitize the message contents before AddData
Regenerate proto types with a protoc-gen-go version compatible with google.golang.org/protobuf in go.mod

Example fix

// before
b, err := proto.Marshal(m) // opaque failure
// after
if err := protocheck.Validate(m); err != nil { // validate first
    return errors.Wrapf(err, "invalid message for snapshot %s", c.file.Name())
}
b, err := proto.Marshal(m)

Defensive patterns

Strategy: try-catch

Validate before calling

if _, err := proto.Marshal(msg); err != nil { return errors.Wrap(err, "message not marshalable") }

Try / catch

if err := w.AddData(k, msg); err != nil {
    return fmt.Errorf("snapshot export aborted while writing key %s: %w", k, err)
}

Prevention

Keep protoc-gen-go and google.golang.org/protobuf versions in sync
Validate message contents before writing to the snapshot
Preserve the wrapped inner error for diagnosis

When it happens

Trigger: proto.Marshal(m) returns an error for a non-nil, valid message — e.g. messages with unmarshalable content, or corrupted in-memory state produced by hand-crafted reflection.

Common situations: Writing snapshot data from messages that failed validation upstream, or using generated proto types from mismatched protoc/runtime versions where marshal hits unsupported fields.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/272517b9b01c2d58. Report an issue: GitHub.