jackc/pgx · error

unable to encode into OID in binary format

Error message

unable to encode %v into OID %d in binary format

What it means

Returned by the binary composite scan plan when Map.PlanScan returns nil for one of the composite's fields — no codec/plan exists to scan that field's OID in binary format into the chosen field target type.

Solutions

1. Change the struct field's Go type to one the field's PostgreSQL type supports
2. Register a custom codec for the field's OID in the TypeMap
3. Scan the composite as text instead of binary

When it happens

Trigger: Thrown at pgtype/composite.go:149 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/1036271ae639b4a2. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/composite.go:149

func (plan *scanPlanBinaryCompositeToCompositeIndexScanner) Scan(src []byte, target any) error {
	targetScanner := (target).(CompositeIndexScanner)

	if src == nil {
		return targetScanner.ScanNull()
	}

	scanner := NewCompositeBinaryScanner(plan.m, src)
	for i, field := range plan.cc.Fields {
		if scanner.Next() {
			fieldTarget, err := compositeFieldTarget(targetScanner, i)
			if err != nil {
				return err
			}
			if fieldTarget != nil {
				fieldPlan := plan.m.PlanScan(field.Type.OID, BinaryFormatCode, fieldTarget)
				if fieldPlan == nil {
					return fmt.Errorf("unable to encode %v into OID %d in binary format", field, field.Type.OID)
				}

				err = fieldPlan.Scan(scanner.Bytes(), fieldTarget)
				if err != nil {
					return err
				}
			}
		} else {
			return errors.New("read past end of composite")
		}
	}

	if err := scanner.Err(); err != nil {
		return err
	}

	return nil
}

View on GitHub (pinned to ec1a0befd2)