Uptime Monitoring Error Codes

Here is a list of the most popular error codes and their descriptions that you can see in your Uptime Monitoring Dashboard:

Status (200 OK). The request to the server has succeeded. Everything is fine.

Error (403 Forbidden). The client does not have access rights to the content; that is, it is unauthorized, so the server is refusing to give the requested resource.

Error (404 Not Found). The server can not find the requested resource. In an API, this can also mean that the endpoint is valid but the resource itself does not exist. Servers may also send this response instead of 403 to hide the existence of a resource from an unauthorized client.

Error (408 Request Timeout). This response is sent on an idle connection by some servers, even without any previous request by the client. It means that the server would like to shut down this unused connection.

Error (409 Conflict). This response is sent when a request conflicts with the current state of the server.

Error (500 Internal Server Error). The server has encountered a situation it doesn't know how to handle.

Error (502 Bad Gateway). This error response means that the server while working as a gateway to get a response needed to handle the request, got an invalid response.

Error (503 Service Unavailable). The server is not ready to handle the request. Common causes are a server that is down for maintenance or that is overloaded.

Error (504 Gateway Timeout). This error response is given when the server is acting as a gateway and cannot get a response in time.

Error (508 Loop Detected). The server detected an infinite loop while processing the request.

Error (520 Web Server Returns an Unknown Error). This error is essentially a catch-all response when something unexpected happens or when the origin server incorrectly interprets or does not tolerate a request due to a protocol violation or an empty response. It occurs when the connection started on the origin web server, but that the request was not completed.

Error (521 Web Server is Down). It happens when the origin web server refuses connections.

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