jackc/pgx · error

invalid length for bit/varbit

Error message

invalid length for bit/varbit: %w

What it means

Reading the 4-byte bit-length header of a binary bit/varbit value failed (truncated or unreadable message); the wrapped pgio error names the underlying read problem.

Solutions

1. Fail the scan; the binary payload is malformed
2. Check for truncated network data or a proxy altering binary results
3. Verify the column is actually bit/varbit and binary format is being used correctly

When it happens

Trigger: Thrown at pgtype/bits.go:174 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/780d755f45aa53af. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/bits.go:174

		return nil, err
	}
	return box, nil
}

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})
}

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