AlexxIT/go2rtc · error

tlv8: unsupported array:

Error message

tlv8: unsupported array: 

What it means

tlv8 supports decoding arrays only when the element kind is uint8 (byte arrays). If a struct field is an array of any other element type, unmarshalValue returns this error naming the unsupported element kind.

Solutions

1. Change the array element type to uint8 (e.g. [6]byte instead of [6]uint16).
2. Use a []byte slice if the length is variable.
3. Decode into a custom type implementing manual unmarshaling for non-byte elements.
4. Split the multi-byte array into multiple scalar uint8/uint16 fields.

Example fix

// before
type T struct {
  Addrs [4]uint16 `tlv8:"2"`
}
// after
type T struct {
  Addrs [8]byte `tlv8:"2"`
}

func tlv8Supported(v reflect.Value) error {
    t := v.Type()
    if t.Kind() == reflect.Array || t.Kind() == reflect.Slice {
        if t.Elem().Kind() != reflect.Uint8 {
            return fmt.Errorf("field %s: only byte arrays supported, got %s", t, t.Elem().Kind())
        }
    }
    return nil
}

func isByteArray(t reflect.Type) bool {
    return (t.Kind() == reflect.Array || t.Kind() == reflect.Slice) && t.Elem().Kind() == reflect.Uint8
}

if err := tlv8.Unmarshal(payload, &msg); err != nil {
    if strings.Contains(err.Error(), "unsupported array") {
        return fmt.Errorf("schema uses non-byte array: %w", err)
    }
    return err
}

When it happens

Trigger: Decoding a TLV8 record into a struct field declared as e.g. [4]uint16, [2]int, or [N]string.

Common situations: Modeling HomeKit TLV fields as typed arrays; refactoring a []byte field to a wider numeric array; copying struct definitions from another protocol.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• tlv8: not implemented:
• tlv8: value should be pointer:
• tlv8: unmarshal zero data
• tlv8: wrong size:
• tlv8: zero item

AI-assisted analysis of AlexxIT/go2rtc@c245815e75 (2026-09-07). Data as JSON: /api/errors/a9344e76b480bac3. Report an issue: GitHub.

Appendix: source

Thrown at pkg/hap/tlv8/tlv8.go:332

		}
		value.SetUint(uint64(v[0]) | uint64(v[1])<<8 | uint64(v[2])<<16 | uint64(v[3])<<24)

	case reflect.Uint64:
		if len(v) != 8 {
			return errors.New("tlv8: wrong size: " + value.Type().Name())
		}
		value.SetUint(binary.LittleEndian.Uint64(v))

	case reflect.Float32:
		f := math.Float32frombits(binary.LittleEndian.Uint32(v))
		value.SetFloat(float64(f))

	case reflect.String:
		value.SetString(string(v))

	case reflect.Array:
		if kind := value.Type().Elem().Kind(); kind != reflect.Uint8 {
			return errors.New("tlv8: unsupported array: " + kind.String())
		}

		for i, b := range v {
			value.Index(i).SetUint(uint64(b))
		}
		return nil

	case reflect.Slice:
		i := growSlice(value)
		return unmarshalValue(v, value.Index(i))

	case reflect.Struct:
		return unmarshalStruct(v, value)

	default:
		return errors.New("tlv8: not implemented: " + value.Kind().String())
	}

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