error marshalling proto message to write to the snapshot fil

Error message

error marshalling proto message to write to the snapshot file: %s: proto: Marshal called with nil

What it means

FileWriter.EncodeProtoMessage refuses to encode a proto message that is nil or invalid before calling proto.Marshal, because protobuf's Marshal panics/errs with 'proto: Marshal called with nil' in that case. The error wraps the snapshot file name so the developer knows which snapshot was being written. It indicates the caller (AddData or the ledger export path) passed an unset/invalid protobuf message into the snapshot encoder.

Source

Thrown at common/ledger/snapshot/file.go:70

	}
	return &FileWriter{
		file:              file,
		bufWriter:         bufWriter,
		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
}

View on GitHub (pinned to 2736b63f8f)

Solutions

Check the proto message for nil/invalid before calling AddData and skip or substitute a valid message
Fix the upstream producer so it never yields a nil message (e.g. return an explicit error when a record is absent)
Log which field/key produced the nil message to locate the corrupt or missing ledger data

Example fix

// before
if err := w.AddData(key, someMsg); err != nil { ... }
// after
if someMsg == nil || !someMsg.ProtoReflect().IsValid() {
    return errors.New("skipping nil proto message for key " + string(key))
}
if err := w.AddData(key, someMsg); err != nil { ... }

Defensive patterns

Strategy: validation

Validate before calling

func validProto(m proto.Message) bool { return m != nil && m.ProtoReflect().IsValid() }
// call: if !validProto(msg) { return errors.New("nil proto message") }

Type guard

func isNilProto(m proto.Message) bool {
    return m == nil || !m.ProtoReflect().IsValid()
}

Try / catch

if err := w.AddData(k, msg); err != nil {
    if strings.Contains(err.Error(), "Marshal called with nil") {
        log.Warnf("skipping nil message for key %s", k); return nil
    }
    return err
}

Prevention

Never pass typed-nil proto pointers to AddData
Check m.ProtoReflect().IsValid() before encoding
Ensure producers of config/collection records return explicit errors instead of nil messages

When it happens

Trigger: Calling AddData/EncodeProtoMessage with a nil proto.Message, or with a typed-nil pointer (e.g. (*pb.SomeMsg)(nil)) whose ProtoReflect().IsValid() is false.

Common situations: Exporting a ledger snapshot where a config or collection record is missing/nil (e.g. empty collection config, unset config history entry), or a lookup returned nil and the code passed it straight to the snapshot writer.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/eeac5bf5b3403f4b. Report an issue: GitHub.