thanos-io/thanos · error

proto: wrong wireType =

Error message

proto: wrong wireType = %d for field MaxTime

What it means

Generated gogoproto Unmarshal guard for field 5 (MaxTime) of the Statistic message in pkg/status/statuspb/rpc.pb.go:1785. Like MinTime, MaxTime must be varint-encoded; the error fires when field 5 arrives with any other wire type, indicating the wire data does not match the compiled schema.

Solutions

  1. Pin both client and server to the same Thanos version so the schema matches
  2. Regenerate the statuspb package from the canonical rpc.proto
  3. Confirm MaxTime is field 5 (varint) in the sender's schema
  4. Log the raw gRPC payload to identify exactly what the sender encoded

Example fix

// before: mixed versions
querier (v0.30) -> store (v0.32)
// after
querier and store upgraded to the same release
Defensive patterns

Strategy: try-catch

Validate before calling

if !semverCompatible(peerVersion, minSupportedVersion) {
    return fmt.Errorf("peer %s version %s incompatible for TSDB statistics", peer, peerVersion)
}

Try / catch

if err := proto.Unmarshal(buf, &stat); err != nil {
    if strings.Contains(err.Error(), "field MaxTime") {
        return fmt.Errorf("schema mismatch (MaxTime): %w", err)
    }
    return err
}

Prevention

When it happens

Trigger: Unmarshaling a Statistic message where field 5 arrives with wire type 1, 2, or 5 instead of varint (0).

Common situations: Thanos component version mismatch; sender generated from a modified rpc.proto; proxy or service mesh mangling gRPC frames; interop with a hand-written protobuf encoder.

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

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/cb8d16c35e8d41d9. Report an issue: GitHub.

Appendix: source

Thrown at pkg/status/statuspb/rpc.pb.go:1785

			}
			m.MinTime = 0
			for shift := uint(0); ; shift += 7 {
				if shift >= 64 {
					return ErrIntOverflowRpc
				}
				if iNdEx >= l {
					return io.ErrUnexpectedEOF
				}
				b := dAtA[iNdEx]
				iNdEx++
				m.MinTime |= int64(b&0x7F) << shift
				if b < 0x80 {
					break
				}
			}
		case 5:
			if wireType != 0 {
				return fmt.Errorf("proto: wrong wireType = %d for field MaxTime", wireType)
			}
			m.MaxTime = 0
			for shift := uint(0); ; shift += 7 {
				if shift >= 64 {
					return ErrIntOverflowRpc
				}
				if iNdEx >= l {
					return io.ErrUnexpectedEOF
				}
				b := dAtA[iNdEx]
				iNdEx++
				m.MaxTime |= int64(b&0x7F) << shift
				if b < 0x80 {
					break
				}
			}
		default:
			iNdEx = preIndex

View on GitHub (pinned to 35b8b99117)