http error 503 the service is unavailable

http error 503 the service is unavailable message pops up when we try to access an application through IIS webserver. Microsoft has mentioned in one of its support links, https://support.microsoft.com/en-in/kb/2619402 that describes the issue and its resolution.

Image for reference below,

As mentioned in the support link, navigate to issue 3 and the resolution mentioned there fixed the issue.

The error occurs if the application pool is set to enable 32-bit applications but is not configured correctly. By default, 32-bit support is disabled on the application pools. If 32-bit support is not required, check the advanced settings of each application pool to make sure that the Enable 32-bit applications value is set to False.

Please note that though this fixed the issue, there are other set of links that has stated the problem and we need to try and see which one can fix the issue. Try to check if the below mentioned fixes can fix the issue.

1. Load User Profile should be False

2. Restart Default Application Pool

Other set of links for reference:

http://forums.iis.net/t/1183179.aspx?Service+Unavailable+HTTP+Error+503+The+service+is+unavailable+

http://www.iis.net/learn/manage/configuring-security/application-pool-identities