sqlmapproject/sqlmap · error · InterfaceError

backend message too large (%d bytes)

Error message

backend message too large (%d bytes)

What it means

Error "backend message too large (%d bytes)" thrown in sqlmapproject/sqlmap.

Source

Thrown at extra/dbwire/mysql.py:78

def _cstring(data, off):
    # NUL-terminated string, tolerant of a missing terminator (returns the remainder)
    end = data.find(b"\x00", off)
    if end == -1:
        return data[off:], len(data)
    return data[off:end], end + 1

def _read_packet(sock):
    header = recvn(sock, 4)
    length = struct.unpack("<I", header[0:3] + b"\x00")[0]
    seq = _u8(header, 3)
    payload = recvn(sock, length)
    total = length
    while length == 0xffffff:  # payload continues in the next packet
        header = recvn(sock, 4)
        length = struct.unpack("<I", header[0:3] + b"\x00")[0]
        total += length
        if total > _MAX_MESSAGE_LENGTH:
            raise InterfaceError("backend message too large (%d bytes)" % total)
        payload += recvn(sock, length)
    return seq, payload

def _send_packet(sock, seq, payload):
    while True:  # split payloads >= 16 MB into 0xffffff-sized packets (with a trailing short packet)
        chunk = payload[:0xffffff]
        try:
            sock.sendall(struct.pack("<I", len(chunk))[0:3] + struct.pack("<B", seq & 0xff) + chunk)
        except (socket.error, OSError) as ex:
            raise connection_lost(ex)
        seq = (seq + 1) & 0xff
        payload = payload[0xffffff:]
        if len(chunk) < 0xffffff:
            break

def _lenc_int(data, off):
    first = _u8(data, off)
    if first < 0xfb:

View on GitHub (pinned to 0a35b20e39)

When it happens

Trigger: Thrown at extra/dbwire/mysql.py:78 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of sqlmapproject/sqlmap@0a35b20e39 (2026-08-26). Data as JSON: /api/errors/84ae90732ff11444. Report an issue: GitHub.