SeleniumHQ/selenium · error · ValueError

Specified proxy type ({compatible_proxy}) not compatible wit

Error message

Specified proxy type ({compatible_proxy}) not compatible with current setting ({self.proxyType})

What it means

A Proxy enforces that proxy settings stay self-consistent: each connection-related property (http_proxy, ssl_proxy, socks_*, no_proxy) is bound to a specific ProxyType (MANUAL or PAC). _verify_proxy_type_compatibility raises ValueError if the current proxyType is neither UNSPECIFIED nor the type that property requires. E.g. setting http_proxy while proxyType is PAC is rejected.

Source

Thrown at py/selenium/webdriver/common/proxy.py:164

    @property
    def proxy_type(self):
        """Returns proxy type as `ProxyType`."""
        return self.proxyType

    @proxy_type.setter
    def proxy_type(self, value) -> None:
        """Sets proxy type.

        Args:
            value: The proxy type.
        """
        self._verify_proxy_type_compatibility(value)
        self.proxyType = value

    def _verify_proxy_type_compatibility(self, compatible_proxy):
        if self.proxyType not in (ProxyType.UNSPECIFIED, compatible_proxy):
            raise ValueError(
                f"Specified proxy type ({compatible_proxy}) not compatible with current setting ({self.proxyType})"
            )

    def to_capabilities(self):
        proxy_caps = {"proxyType": self.proxyType["string"].lower()}
        proxies = [
            "autodetect",
            "httpProxy",
            "proxyAutoconfigUrl",
            "sslProxy",
            "noProxy",
            "socksProxy",
            "socksUsername",
            "socksPassword",
            "socksVersion",
        ]
        for proxy in proxies:
            attr_value = getattr(self, proxy)

View on GitHub (pinned to aa36b38e69)

Solutions

1. Set proxy_type = ProxyType.MANUAL before assigning http/ssl/socks/no_proxy properties.
2. For PAC, set proxy_autoconfig_url and proxy_type = ProxyType.PAC; do not set manual hosts.
3. If reusing a Proxy, reset proxy_type to UNSPECIFIED before reconfiguring.

Example fix

# before
proxy.proxy_type = ProxyType.PAC
proxy.http_proxy = 'localhost:8080'  # PAC != MANUAL -> ValueError

# after
proxy.proxy_type = ProxyType.MANUAL
proxy.http_proxy = 'localhost:8080'
# or for PAC
proxy.proxy_type = ProxyType.PAC
proxy.proxy_autoconfig_url = 'http://host/proxy.pac'

from selenium.webdriver.common.proxy import ProxyType
# Ensure MANUAL before setting host-type properties
if proxy.proxyType not in (ProxyType.UNSPECIFIED, ProxyType.MANUAL):
    proxy.proxy_type = ProxyType.MANUAL
proxy.http_proxy = 'localhost:8080'

try:
    proxy.http_proxy = host
except ValueError:
    proxy.proxy_type = ProxyType.MANUAL
    proxy.http_proxy = host

When it happens

Trigger: Setting proxy.http_proxy = 'host' when proxyType is already PAC or AUTODETECT. Setting proxy.socks_proxy after setting proxyType = PAC. The order of assignment matters: once proxyType is committed to a non-MANUAL type, MANUAL-bound properties fail.

Common situations: Setting the proxy type first to the wrong value, then trying to add host details. Reusing a Proxy object across configurations. Mixing PAC and manual host settings.

Related errors

• No proxy type is found for {value}
• unknown option#{'s' if not_allowed.size != 1}: #{not_allowed
• invalid proxy type: #{type.inspect}, expected one of #{TYPES
• Unexpected compiled output format. Expected it to start with
• Unexpected compiled output format. Expected it to start with

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/c10d75b9600cc466. Report an issue: GitHub.