jackc/pgx · error

is greater than maximum value for uint8

Error message

%d is greater than maximum value for uint8

What it means

Range guard converting an int64 into Go uint8: the value exceeds math.MaxUint8 and would overflow, so the conversion is refused.

Solutions

1. Scan into a wider unsigned/signed type (uint16, uint32, int64)
2. Constrain the column or query results to the 0-255 range

When it happens

Trigger: Thrown at pgtype/builtin_wrappers.go:142 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/8479bb007376649d. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/builtin_wrappers.go:142

func (w intWrapper) Int64Value() (Int8, error) {
	return Int8{Int64: int64(w), Valid: true}, nil
}

type uint8Wrapper uint8

func (w uint8Wrapper) SkipUnderlyingTypePlan() {}

func (w *uint8Wrapper) ScanInt64(v Int8) error {
	if !v.Valid {
		return fmt.Errorf("cannot scan NULL into *uint8")
	}

	if v.Int64 < 0 {
		return fmt.Errorf("%d is less than minimum value for uint8", v.Int64)
	}
	if v.Int64 > math.MaxUint8 {
		return fmt.Errorf("%d is greater than maximum value for uint8", v.Int64)
	}
	*w = uint8Wrapper(v.Int64)

	return nil
}

func (w uint8Wrapper) Int64Value() (Int8, error) {
	return Int8{Int64: int64(w), Valid: true}, nil
}

type uint16Wrapper uint16

func (w uint16Wrapper) SkipUnderlyingTypePlan() {}

func (w *uint16Wrapper) ScanInt64(v Int8) error {
	if !v.Valid {
		return fmt.Errorf("cannot scan NULL into *uint16")
	}

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