“Service Unavailable HTTP Error 503. This service is unavailable.” – Generic IIS Error Message

Target Audience: IT Manager
Article #: 11892


During the BreadCrumbs setup, a user received an error message reading “Service Unavailable HTTP Error 503. This service is unavailable.” This article explains the cause behind this IIS error message as well as the steps need to resolve the issue.

HTTP Error 503 message


The HTTP Error 503 message indicates that an IIS service is unavailable. We found, during our troubleshooting process, that a needed Application Pool was stopped.

The WSTrackTrace Application Pool is stopped

To determine the cause of the stoppage, right-click on the affected Application Pool.

Right-click on the stopped process to determine the cause.

This will open the Advanced Settings window. If Rapid-Fail Protection was triggered, it will display the information.

The Advanced Settings window for the WSTrackTrace Application Pool showing the Fail Protection settings

In this case, IIS had stopped the Application Pool after multiple 500.19 Internal Service Errors occurred. This caused IIS to exceed the Rapid-Fail Protection set in the Advanced Settings of the Application Pool.


If the 503 IIS response is shown to be caused by Rapid-Fail Protection triggered by other error(s), then you must first resolve them. Restart the Application Pool and see if you can determine the cause of the shutdown. Once those source error(s) are addressed, IIS should work properly.

Additional Comments

Issue found in Windows 2016

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