List of 5xx HTTP Status Codes with Explanation
5xx HTTP Status Codes - Server Error
These are the HTTP status or error codes most frequently seen in the web browser window. 5xx error codes are returned by the web server when it encounters a problem during processing of the requested resource by the client.
500 - Internal server error
When the server encountered an unexpected condition which stops it from responding to the request then it returns an error code "500 - Internal Server Error".
501 - Method not supported
When the server does not able to provide the requested resource due to unsupported or unrecognized method used in the request then the code "501 - Not Implemented is received.
502 - Gateway error
When a request prompts the server1 to act as a gateway or proxy to get a response from another server2 and if the server1 received an unacceptable response from the server2 then the code "502 - Bad Gateway" is received.
503 - Service unavailable
When a request is received by the server at the time it is overloaded by other requests or it is under planned maintenance downtime then the code "503 - Service Unavailable" is received.
504 - Gateway timeout
When the server1 is acting as an external gateway or proxy and did not receive the response on time from the next server2 further up in the request chain which it tried to access in order to fulfil the request then code "504 - Gateway Timeout" is received.
505 - HTTP version is not supported
When the server does not support the HTTP protocol version used in the request message then the code "505 - HTTP Version Not Supported" is received.
507 - Insufficient space
When the server runs out of hard disk space and no more accommodate the request then the code "507 - Insufficient Storage" is received.
510 - Extensions are Missing
When the server can't process the request due to unsupported extension is requested then the code "510 - Not Extended" is received.