What is the meaning of "the server responded with a status of 502 ()" error when trying to load a resource?

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The 502 error is a HTTP status code that indicates that a server received an invalid response from a upstream server it accessed to complete the request. This can happen due to various reasons such as server overload, connection timeouts, DNS resolution failures, or server misconfiguration. In simple terms, it means that the server could not complete the request and return the required resource.