# HTTP Error Response codes | Error code | Description | | --------------------------------------- | ------------------------------------------------------------------------------------------------------- | | **400 Bad Request** | Request did not contain a host to connect to or if there was a generic error when validating a request. | | **403 Forbidden** | Error when validating ACL for request. | | **407 Proxy Authentification Required** | Request lacks proxy authentication information, or username or password is invalid. | | **429 Hard limit reached** | Hard limit value reached, sending additional IP requests is blocked. | | **500 Internal server error** | Proxy server has encountered an internal error. | | **502 Bad Gateway** | Error when request proxying encountered an error. | | **504 Timeout** | A proxy server did not receive a response from the upstream server in time. Try again. | | **525 Exit node missing** | Error shown when no exit node was found to complete the request. | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.goproxies.com/proxies/http-error-response-codes.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.