What causes "x-tunnel login_session fail, session not start" in XX-net/XX-Net?

Verify login_username/login_password in your x-tunnel config are correct and the account is active with remaining quota.

XX-net/XX-Net · critical

x-tunnel login_session fail, session not start

Error message

x-tunnel login_session fail, session not start

What it means

proxy_session.start() initializes transfer state and then calls login_session() to authenticate with the x-tunnel server; when login fails (bad credentials, unreachable server, or API error) start() logs this warning and returns False, so the session never sets running=True and no worker threads are spawned.

Source

Thrown at code/default/x_tunnel/local/proxy_session.py:149

            self.traffic_upload = 0
            self.traffic_download = 0
            self.last_traffic_upload = 0
            self.last_traffic_download = 0
            self.last_traffic_reset_time = time.time()

            # sn => (payload, send_time)
            # sn => ack
            self.wait_ack_send_list = dict()
            self.ack_send_continue_sn = 0

            self.received_sn = []
            self.receive_next_sn = 1
            self.target_on_roads = 0
            self.server_time_offset = 0
            self.server_time_deviation = 9999

            if not self.login_session():
                xlog.warn("x-tunnel login_session fail, session not start")
                return False

            self.running = True

            for i in range(0, g.config.concurent_thread_num):
                if i in self.round_trip_thread:
                    continue

                self.round_trip_thread[i] = threading.Thread(target=self.normal_round_trip_worker, args=(i,),
                                                             name="roundtrip_%d" % i)
                self.round_trip_thread[i].start()

            self.connection_pipe.start()
            xlog.info("session started.")
            return True

    def timeout_checker(self):
        while self.running:

View on GitHub (pinned to cfa5bc17b6)

Solutions

Verify login_username/login_password in your x-tunnel config are correct and the account is active with remaining quota.
Check network/DNS access to the x-tunnel API server and retry after transient outages.
Inspect preceding log lines for the specific login_session failure reason (HTTP status, API error message).
If credentials were rotated, update config and restart the tunnel.

Defensive patterns

Strategy: fallback

Validate before calling

ok = session.start()
if not ok:
    # fall back to direct connection or another proxy
    switch_to_direct()

Type guard

def can_start(session) -> bool:
    return bool(session.login_session()) if hasattr(session, 'login_session') else True

Prevention

Verify credentials and account quota before starting the session.
Fail over to a direct/alternate route when start() returns False.
Alert on repeated login failures rather than silently retrying forever.

When it happens

Trigger: Calling start() with an incorrect login_username/login_password, an expired/invalid account, or when the control API server is unreachable, causing login_session() to return False.

Common situations: Wrong or expired x-tunnel credentials in config; account out of quota; server-side migration/URL change; DNS or firewall blocking the API endpoint; system clock skew breaking auth.

Related errors

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/34e5f320952d233d. Report an issue: GitHub.