HelloZeroNet/ZeroNet · error · AnnounceError

Could not connect

Error message

Could not connect

What it means

AnnounceBitTorrentPlugin announces a site's peers via a UDP BitTorrent tracker. announceTrackerUdp calls tracker.connect() then poll_once(); if the first poll returns nothing (no UDP response / connect handshake failed), it raises AnnounceError("Could not connect"). This means the tracker never responded to the initial connection, so the announce cannot proceed.

Source

Thrown at plugins/AnnounceBitTorrent/AnnounceBitTorrentPlugin.py:61

            handler = super(SiteAnnouncerPlugin, self).getTrackerHandler(protocol)
        return handler

    def announceTrackerUdp(self, tracker_address, mode="start", num_want=10):
        s = time.time()
        if config.disable_udp:
            raise AnnounceError("Udp disabled by config")
        if config.trackers_proxy != "disable":
            raise AnnounceError("Udp trackers not available with proxies")

        ip, port = tracker_address.split("/")[0].split(":")
        tracker = UdpTrackerClient(ip, int(port))
        if helper.getIpType(ip) in self.getOpenedServiceTypes():
            tracker.peer_port = self.fileserver_port
        else:
            tracker.peer_port = 0
        tracker.connect()
        if not tracker.poll_once():
            raise AnnounceError("Could not connect")
        tracker.announce(info_hash=self.site.address_sha1, num_want=num_want, left=431102370)
        back = tracker.poll_once()
        if not back:
            raise AnnounceError("No response after %.0fs" % (time.time() - s))
        elif type(back) is dict and "response" in back:
            peers = back["response"]["peers"]
        else:
            raise AnnounceError("Invalid response: %r" % back)

        return peers

    def httpRequest(self, url):
        headers = {
            'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11',
            'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
            'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.3',
            'Accept-Encoding': 'none',
            'Accept-Language': 'en-US,en;q=0.8',

View on GitHub (pinned to 454c0b2e7e)

Solutions

  1. Verify the tracker address is alive (e.g. test with a bittorrent client or dig/nc for the UDP port).
  2. Check local firewall/NAT allows outbound UDP on the tracker port.
  3. Wait and retry — announce is retried periodically and other trackers (AnnounceTrackers plugin) cover failures.
  4. Replace the dead tracker in the site's tracker list.
  5. Check Tor/transparent proxy config is not blocking UDP.

Example fix

// before
tracker.connect()
if not tracker.poll_once():
    raise AnnounceError("Could not connect")
// after
tracker.connect()
if not tracker.poll_once():
    self.site.log.debug("UDP tracker %s unreachable, skipping" % tracker_address)
    return []  # let other trackers handle announce
Defensive patterns

Strategy: retry

Validate before calling

import socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.settimeout(5)
try:
    host, port = tracker_address.split(":")
    sock.sendto(b"probe", (socket.gethostbyname(host), int(port)))
    reachable = True
except (socket.error, socket.gaierror):
    reachable = False
finally:
    sock.close()
if not reachable:
    skip_tracker(tracker_address)

Try / catch

try:
    peers = announce_plugin.announceTrackerUdp(tracker_address, file_info)
except AnnounceError as e:
    log.warning("UDP tracker %s failed: %s" % (tracker_address, e))
    peers = []  # other announce plugins will cover

Prevention

When it happens

Trigger: The UDP tracker at the configured tracker address is unreachable or drops packets: tracker domain resolves wrong, UDP traffic blocked by firewall/NAT, tracker offline, or wrong port in the site's tracker list. tracker.poll_once() times out after tracker.connect().

Common situations: Firewalled/censored networks blocking UDP; dead public BitTorrent trackers; trackers configured in site's sites.json that no longer exist; IPv6 vs IPv4 mismatch (getIpType check sets peer_port=0 but tracker still unresponsive).

Related errors

AI-assisted analysis of HelloZeroNet/ZeroNet@454c0b2e7e (2026-09-02). Data as JSON: /api/errors/7d3b062719596667. Report an issue: GitHub.