jackc/pgx · error

unable to encode

Error message

unable to encode %v

What it means

When encoding a multirange to text, the encoder reflects over each element and re-plans the element's encode step whenever the element's Go type changes. This guard fires when no encode plan can be found for an element — the element's type is not encodable to the multirange's element type OID (e.g. a Go type not registered for the underlying range subtype).

Solutions

1. Ensure all elements share a Go type registered for the multirange's element type via RegisterDefaultPgType
2. Scan into a typed Multirange[Range[T]] instead of a mixed-type slice
3. Remove unsupported element types from the slice before encoding

When it happens

Trigger: Thrown at pgtype/multirange.go:113 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /api/errors/ae2c92efafada2e4. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/multirange.go:113

	buf = append(buf, '{')

	var encodePlan EncodePlan
	var lastElemType reflect.Type
	inElemBuf := make([]byte, 0, 32)
	for i := range elementCount {
		if i > 0 {
			buf = append(buf, ',')
		}

		elem := multirange.Index(i)
		var elemBuf []byte
		if elem != nil {
			elemType := reflect.TypeOf(elem)
			if lastElemType != elemType {
				lastElemType = elemType
				encodePlan = p.m.PlanEncode(p.ac.ElementType.OID, TextFormatCode, elem)
				if encodePlan == nil {
					return nil, fmt.Errorf("unable to encode %v", multirange.Index(i))
				}
			}
			elemBuf, err = encodePlan.Encode(elem, inElemBuf)
			if err != nil {
				return nil, err
			}
		}

		if elemBuf == nil {
			return nil, fmt.Errorf("multirange cannot contain NULL element")
		} else {
			buf = append(buf, elemBuf...)
		}
	}

	buf = append(buf, '}')

	return buf, nil

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