We've recently had an issue where our application/website was displaying "The service is unavailable" message to users. Please note it wasn't the typical message where it displays the 503 error code that IIS typically generates...the only text on the page was "The service is unavailable" (it did not show any error codes or any additional text).
We stopped the application pool and started it back up, and the site began to work again. It was down for approximately 15 minutes.
We've gone through all of the log files and interestingly enough there was some traffic going to the server during the 15 minutes we were seeing the "The services is unavailable" message, without any 503 attempts being logged, no windows event errors, etc.
Does anyone have any ideas how to isolate the issue or find a log file that would display what happened?