dgraph-io/dgraph · error

while parsing kv: %+v, got error: %v

Error message

while parsing kv: %+v, got error: %v

What it means

batchAndProposeKeyValues (predicate move receiver on the destination leader) parses the first received KV to discover the predicate and expects the very first key to be a schema key. This error is raised inside the SliceIterate when x.Parse fails on that first KV — meaning the streamed KV batch starts with an unparseable key, so the receiver cannot determine which predicate/schema the move carries.

Source

Thrown at worker/predicate_move.go:77

func batchAndProposeKeyValues(ctx context.Context, kvs chan *pb.KVS) error {
	glog.Infoln("Receiving predicate. Batching and proposing key values")
	n := groups().Node
	proposal := &pb.Proposal{}
	size := 0
	var pk x.ParsedKey

	for kvPayload := range kvs {
		buf := z.NewBufferSlice(kvPayload.GetData())
		err := buf.SliceIterate(func(s []byte) error {
			kv := &bpb.KV{}
			x.Check(proto.Unmarshal(s, kv))
			if len(pk.Attr) == 0 {
				// This only happens once.
				var err error
				pk, err = x.Parse(kv.Key)
				if err != nil {
					return errors.Errorf("while parsing kv: %+v, got error: %v", kv, err)
				}

				if !pk.IsSchema() {
					return errors.Errorf("Expecting first key to be schema key: %+v", kv)
				}

				// Delete on all nodes. Remove the schema at timestamp kv.Version-1 and set it at
				// kv.Version. kv.Version will be the TxnTs of the predicate move.
				p := &pb.Proposal{CleanPredicate: pk.Attr, StartTs: kv.Version - 1}
				glog.Infof("Predicate being received: %v", pk.Attr)
				if err := n.proposeAndWait(ctx, p); err != nil {
					glog.Errorf("Error while cleaning predicate %v %v\n", pk.Attr, err)
					return err
				}
			}

			proposal.Kv = append(proposal.Kv, kv)
			size += len(kv.Key) + len(kv.Value)

View on GitHub (pinned to 759e242be6)

Solutions

1. Retry the predicate move; verify source and destination run identical Dgraph versions.
2. Re-run with verbose glog to see the offending KV and compare its key bytes with a known-good schema key prefix.
3. Validate the source predicate data with `dgraph debug` before moving.
4. If the stream is corrupted, restart both Alphas involved and re-trigger the move from Zero.

pk, err := x.Parse(firstKV.Key)
if err != nil {
	return errors.Errorf("first streamed KV has invalid key: %v", err)
}

func parsableKey(key []byte) bool {
	_, err := x.Parse(key)
	return err == nil
}

if err := batchAndProposeKeyValues(ctx, kvs); err != nil && strings.Contains(err.Error(), "while parsing kv") {
	// cancel stream, verify sender version/encoding, retry move
}

When it happens

Trigger: During ReceivePredicate streaming, the first KV in the first payload fails x.Parse: sender sent KVs not prefixed with a valid Dgraph key, version-mismatched key encoding between source and destination Alphas, or corrupted KV bytes.

Common situations: Moving a tablet between clusters or versions with different key layouts; a sender-side bug/backup restore yielding malformed first key; network-level corruption of the gRPC stream payload buffer.

Related errors

• while parsing KV: %+v, got error: %v
• Expecting first key to be schema key: %+v
• illegal rune found "%c", expecting {
• JSON map is followed by illegal rune "%c"
• Malformed JSON

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/82b2ec2c6b32fd36. Report an issue: GitHub.