HTTP Status Codes

HTTP 503 Service Unavailable

By Error Admin in 5xx Server Error Code, HTTP Status Codes

HTTP 503 error code: The HTTP 503 Service Unavailable Error is an HTTP status code that means that the site has met the maximum simultaneous connections or visitors. And the temporary overloading to handle the HTTP requests may lead to the HTTP 503 Error. Certain servers simply refuse the socket connection in this state leading to a different error like socket creation timed out.

HTTP 503 Error Code

HTTP 503 Error Code

The 503 Error may appear on any browser and operating systems such as Windows 10/8.1/8/Vista/XP, Mac and Linux if it has an active internet connection and the above-mentioned scenario occurs. HTTP Status Codes.

List of 503 Error messages

The HTTP 503 Error Code displays in various terms depending upon the website it appears. Also, it relies on the server software that generates the message. Here are the various ways by which the Service Unavailable 503 Error appears.

  • 503 Error
  • HTTP 503
  • HTTP Error 503
  • Error 503 Service Unavailable
  • 503 Service Unavailable
  • 503 Service Temporarily Unavailable
  • Http/1.1 Service Unavailable
  • HTTP Server Error 503
  • Service Unavailable – DNS Failure

Reasons for 503 Service Unavailable Error

These are the variety of reasons that the HTTP 503 Errors are encountered because of,

  • The server cannot start any new work processes because of the limited system resources
  • The connection limit for the site or server as a whole has been reached
  • The application pool has been put into Rapid Fail Protection and has been disabled automatically
  • The administrator has stopped the application pool
  • Starting a new work process would exceed the DemandStartThresholdproperty
  • Bandwidth throttling is enabled, but the filter addition fails
  • The application pool is too busy to handle the request. The request has, therefore, timed out in the queue and had been returned with a 503 error
  • The control channel or internal configuration group for the URL is inactive.
  • The send for a request that was serviced from the cache failed

Usually, the message that is sent to the client regarding the error is limited due to security reasons. The error log is kept private by the HTTP.sys. As these HTTP errors never enter the user mode, the error log is the only place where the problems are stored.

Fix 503 Service Unavailable

The common methods that will help you get rid of HTTP 503 Errors are

  1. Check the event logs. Typically, the event logs contain more detailed information about the cause of a 503 error
  2. Verify that health/recycling issues are not causing the error
  3. Restart the router and modem especially if you see the “Service Unavailable – DNS Failure” error
  4. Check for the server binding conflicts
  5. Check the IP inclusion list for errors
  6. Contact the website directly for help
  7. Try again later. As this 503 Error might retard as the visitors gets reduced. Hence if more visitors leave the site, the more likely the website would load

HTTP 503 Code References

The code references for the HTTP 503 Error Code are

  • Rails HTTP Status Symbol :service_unavailable
  • Go HTTP Status Constant http.StatusServiceUnavailable
  • Symfony HTTP Status Constant Response::HTTP_SERVICE_UNAVAILABLE
  • Python2 HTTP Status Constant httplib.SERVICE_UNAVAILABLE
  • Python3+ HTTP Status Constant http.client.SERVICE_UNAVAILABLE
  • Python3.5+ HTTP Status Constant http.HTTPStatus.SERVICE_UNAVAILABLE

There are several other errors that exist on the server side like HTTP 404 Error. Know more about HTTP Status codes from here Error Codes List.

    1 Comment

  1. hi quality posts.


    January 28, 2017

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