RustPython/RustPython · error · OSError

could not bind on any address out of %r

Error message

could not bind on any address out of %r

What it means

Raised by create_server when, after resolving the host(s), no socket could be bound at all - every bind attempt either failed or was skipped as EADDRNOTAVAIL (Lib/asyncio/base_events.py:1640). The message lists all candidate addresses that were tried. It usually means the requested address is not assigned to this machine - most often an IPv6 address on an IPv4-only host, or a hardcoded IP from another environment.

Source

Thrown at Lib/asyncio/base_events.py:1640

                                        socket.IPV6_V6ONLY,
                                        True)
                    try:
                        sock.bind(sa)
                    except OSError as err:
                        msg = ('error while attempting '
                               'to bind on address %r: %s'
                               % (sa, str(err).lower()))
                        if err.errno == errno.EADDRNOTAVAIL:
                            # Assume the family is not enabled (bpo-30945)
                            sockets.pop()
                            sock.close()
                            if self._debug:
                                logger.warning(msg)
                            continue
                        raise OSError(err.errno, msg) from None

                if not sockets:
                    raise OSError('could not bind on any address out of %r'
                                  % ([info[4] for info in infos],))

                completed = True
            finally:
                if not completed:
                    for sock in sockets:
                        sock.close()
        else:
            if sock is None:
                raise ValueError('Neither host/port nor sock were specified')
            if sock.type != socket.SOCK_STREAM:
                raise ValueError(f'A Stream Socket was expected, got {sock!r}')
            sockets = [sock]

        for sock in sockets:
            sock.setblocking(False)

        server = Server(self, sockets, protocol_factory,

View on GitHub (pinned to aaeab4f754)

Solutions

1. Bind all interfaces instead: host='' (or '0.0.0.0' / '::')
2. Verify the address is assigned: ip addr show / ifconfig, or wait for the interface at startup
3. Remove stale addresses from the host list; keep only addresses present on this host

Example fix

# before
server = await loop.create_server(factory, '10.0.0.5', 8080)

# after
server = await loop.create_server(factory, '0.0.0.0', 8080)  # or '' for all families

import socket

def local_ips():
    ips = {'127.0.0.1', '::1'}
    for target in ('8.8.8.8', '2001:4860:4860::8888'):
        fam = socket.AF_INET6 if ':' in target else socket.AF_INET
        s = socket.socket(fam, socket.SOCK_DGRAM)
        try:
            s.connect((target, 53))
            ips.add(s.getsockname()[0])
        except OSError:
            pass
        finally:
            s.close()
    return ips

if bind_host not in ('', '*', None) and bind_host not in local_ips():
    raise ValueError(f'{bind_host!r} is not a local address')

try:
    server = await loop.create_server(factory, bind_host, port)
except OSError as e:
    if 'could not bind on any address' in str(e):
        logger.warning('%s not bindable; falling back to all interfaces', bind_host)
        server = await loop.create_server(factory, '', port)
    else:
        raise

When it happens

Trigger: create_server(factory, host='::1', port=8080) on a system without IPv6; host=['10.0.0.5'] where 10.0.0.5 belongs to another machine; every address in a multi-host list failing.

Common situations: Hardcoded per-environment IPs drifting between machines; IPv6 enabled in config but disabled in containers/CI; network interfaces not up yet when the service starts during early boot.

Related errors

• error while attempting to bind on address %r: %s
• getaddrinfo({host!r}) returned empty list
• Neither host/port nor sock were specified
• 2nd arg must be a tuple
• server {self!r} is already being awaited on serve_forever()

AI-assisted analysis of RustPython/RustPython@aaeab4f754 (2026-08-17). Data as JSON: /api/errors/1b4f3f4ab619205c. Report an issue: GitHub.