In this article we will go through the steps which are required to solve Http Error 503 service unavailable on IIS. One possible reason due to which 503 error is coming up due to app pool is stopped on IIS.

Steps to resolve HTTP Error 503 on IIS:

Step 1: Open IIS and right click on website which is throwing Error 503 and then select the option Advanced Settings as shown in below screenshot:

 

Step 2: In Advanced Settings check out the App Pool name of the website and then close this window as shown below:

Step 3: Now as you know app pool associated with your website. Select the option Application Pools in IIS. This option will list out all the app pools for the website which are hosted on IIS. Notice that app pool of your website which is throwing error 503 service unavailable is stopped. Right click on the App Pool name of the website and then select Start as shown below:

 

Open the website in browser and you will see that site is coming up fine. By using these steps you can resolve Http Error 503. Let me know in comment section if you face any difficulty.