KES -> Configure -> Define Profile it gives the following error message.
KES 2.3 encountered an error while processing this page.
Please contact Kaseya Support if the problem persists.
c:\Kaseya\WebPages\AntivirusTab\ManageProfiles.aspx.cs(495): error CS0104:
1. open iis manager
2. browse to application pool, check for below shown setting
Here is the app pool that should be listed in there
If this application is not there in that default app pool then you basically have to look for this application
Most likely it would be listed under app pool asp.net v4.0. Right click that app pool>view application and verify if \Antivirus application is listed in that pool.
If yes, right click this application and click on change application pool and move it to default app pool
Now do the iisreset in command line