A "502 Bad Gateway" error is an HTTP status code that means a server acting as a gateway or proxy received an invalid or bad response from an upstream server it tried to communicate with while attempting to fulfill a request. Essentially, one server on the internet tried to get information from another server but got an invalid or no response, causing the error

What it means:

• A gateway or proxy server (an intermediary server) is involved.
• This server tried to connect to another server (upstream or backend server).
• The upstream server sent back an invalid response or no response at all.
• The error is a server-side issue, not a problem with your device or internet connection

Common causes of a 502 Bad Gateway error:

• Server overload: The upstream server is overwhelmed with requests and cannot respond properly.
• Network issues: Problems in communication between servers, such as DNS errors, routing problems, or timeouts.
• Faulty server software or configuration: Bugs, misconfigurations, or software crashes on the backend server.
• Security software interference: Firewalls or security systems blocking or interrupting server communication.
• Temporary glitches: Short-term server hiccups or connectivity issues.
• DNS problems: The gateway server cannot resolve the IP address of the backend server

Variations of the error message:

• "502 Bad Gateway"
• "502 Proxy Error"
• "502 Service Temporarily Overloaded"
• "502 Bad Gateway Cloudflare" (specific to Cloudflare proxy)
• "502 Bad Gateway Nginx" or "502 Bad Gateway Apache" (specific to web server software)
• "HTTP Error 502 – Bad Gateway"
• Sometimes just a blank white screen with no message

Summary:

The 502 Bad Gateway error indicates a failure in communication between servers on the web, where the intermediary server cannot get a valid response from the upstream server. It is a server-side error often caused by overload, network problems, misconfigurations, or temporary issues