How to solve iis sever error 503

Hi Guys

I have shopping portals there are many users engaged with my website. sometimes I have the error like below.

HTTP Error 503 - Service is unavailable

Please help me to solve this problem. I would really appreciate your help.


Hi! Do you know if you have a bandwidth limit? Also is this what your users are seeing, you are seeing or both?


Hi Buddy check this helpful article.I think it will help you


@JaydeBell You also might want to pre-configure the restart of the AppPool. At work, we schedule all AppPools to recycle every 24-hours. By default, IIS AppPools recycles every 29-hours. This might eliminate some errors.

If you are still having troubles, I would review all logs to determine the source of any errors.

The 503 Service Unavailable error occurs because the server is too busy or maintenance being performed on it so this error may be occurred.

  1. Refresh url to reload.
  2. Check your internet connection or restart your modem

If the error is due to a stopped application pool, then usually starting it would resolve the issue. From the IIS Manager -> Application Pools node, right click on the DefaultAppPool to check the status. On noticing that the service is stopped, we start it

Did you do any stress test before going to production ?
How your app worked on that tests ?

A 503 error usually comes from a proxy server when it can’t contact the backend server. This is due to either misconfiguring the proxy to point at the wrong IP address or port, or when the app serving the backend has crashed.

Closely related is a 504 Gateway Timeout error, when the proxy times out trying to connect to the backend. That can happen with a proxy misconfiguration too, but also if your backend app is locked up but not completely down.

Mind you, any app can send back any HTTP exception, so you can’t always assume an error code means what it says, but you can generally rely on these.

When you start getting 503 and 504 errors intermittently, then it’s time to look at different hosting providers. If you’re getting them 100% of the time, chances are it’s your backend’s fault and problem.