mitmproxy/mitmproxy · error · ValueError

invalid port: {port_str}

Error message

invalid port: {port_str}

What it means

Error "invalid port: {port_str}" thrown in mitmproxy/mitmproxy.

Source

Thrown at mitmproxy/proxy/mode_specs.py:121

        head, _, listen_at = spec.rpartition("@")
        if not head:
            head = listen_at
            listen_at = ""

        mode, _, data = head.partition(":")

        if listen_at:
            if ":" in listen_at:
                host, _, port_str = listen_at.rpartition(":")
            else:
                host = None
                port_str = listen_at
            try:
                port = int(port_str)
                if port < 0 or 65535 < port:
                    raise ValueError
            except ValueError:
                raise ValueError(f"invalid port: {port_str}")
        else:
            host = None
            port = None

        try:
            mode_cls = ProxyMode.__types[mode.lower()]
        except KeyError:
            raise ValueError(f"unknown mode")

        if not issubclass(mode_cls, cls):
            raise ValueError(f"{mode!r} is not a spec for a {cls.type_name} mode")

        return mode_cls(
            full_spec=spec, data=data, custom_listen_host=host, custom_listen_port=port
        )

    def listen_host(self, default: str | None = None) -> str:
        """

View on GitHub (pinned to 2ac5b089d9)

When it happens

Trigger: Thrown at mitmproxy/proxy/mode_specs.py:121 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mitmproxy/mitmproxy@2ac5b089d9 (2026-08-26). Data as JSON: /api/errors/bb6e94836fff7f9f. Report an issue: GitHub.