Summary

The error message 502 Bad Gateway signifies an unresolvable HTTP response in the OpenResty server's configuration. This error indicates that a service attempting to connect to another server is refusing connections and returning an HTTP 502 status code. The primary cause of this failure is typically an invalid HTTP version string in the upstream server's configuration file. OpenResty attempts to send a specific HTTP request (such as GET or POST) to the target server using that protocol, but the server rejects it because it is not recognized as a valid HTTP protocol. This discrepancy between the requested request format and the available protocols in the server's config file prevents the connection from being established, resulting in the 502 Bad Gateway error message.

To resolve this critical connection issue, one must first verify the exact line in the OpenResty configuration file containing the request. If the error message specifies a specific protocol like TCP or HTTP, that exact string should be included in the configuration file to ensure the server understands the communication method. Additionally, checking for typos, missing spaces, or formatting errors in the file can further prevent the error from occurring. It is also recommended to ensure the server's HTTP version is set correctly by searching for the version number in the configuration, which may be stored in a separate settings file.

Title

502 Bad Gateway

Description

502 Bad Gateway

Keywords

gateway

Categories

Communication

NS Lookup

A 116.198.56.7

Dates

Created 2025-11-10

Updated 2026-01-27

Summarized 2026-03-22