jackc/pgx · error

invalid length for bit/varbit: bitLen=

Error message

invalid length for bit/varbit: bitLen=%d

What it means

The binary bit/varbit length header decoded to a negative value, which is impossible on the wire; guards against corrupt or malicious data before computing byte counts.

Solutions

1. Discard the malformed value and fail the query
2. Check for data corruption between server and client
3. Verify a custom encoder is not sending negative lengths

When it happens

Trigger: Thrown at pgtype/bits.go:177 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/4127b0bd5866d1c3. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/bits.go:177

}

type scanPlanBinaryBitsToBitsScanner struct{}

func (scanPlanBinaryBitsToBitsScanner) Scan(src []byte, dst any) error {
	scanner := (dst).(BitsScanner)

	if src == nil {
		return scanner.ScanBits(Bits{})
	}

	r := pgio.NewReader(src)

	bitLen := r.Int32()
	if err := r.Err(); err != nil {
		return fmt.Errorf("invalid length for bit/varbit: %w", err)
	}
	if bitLen < 0 {
		return fmt.Errorf("invalid length for bit/varbit: bitLen=%d", bitLen)
	}

	// Finish rejects trailing bytes, so together with the read below the data
	// must be exactly the number of bytes bitLen calls for.
	data := r.Bytes((int(bitLen) + 7) / 8)
	if err := r.Finish(); err != nil {
		return fmt.Errorf("invalid length for bit/varbit: bitLen=%d: %w", bitLen, err)
	}

	buf := make([]byte, len(data))
	copy(buf, data)

	return scanner.ScanBits(Bits{Bytes: buf, Len: bitLen, Valid: true})
}

type scanPlanTextAnyToBitsScanner struct{}

func (scanPlanTextAnyToBitsScanner) Scan(src []byte, dst any) error {

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