When a user is unsuccessful in authenticating to AuthAnvil with the Kaseya Logon Agent, the system displays the error: "An error occurred on the server when processing the URL. Please contact the system administrator. If you are the system administrator please click here to find out more about this error."
This issue is caused due to a communication problem between IIS on the Kaseya box and the client browser.
Open up the AuthAnvil.asp file located at C:\kaseya\WebPages\AuthAnvil\inc\AuthAnvil.asp, and on line 469, comment out the line by adding a pair of slashes in front of it, so that it reads
//Response.Cookies("sessionId") = -1;
Then save the file.
AuthAnvil Kaseya Logon Agent 1.5, and AuthAnvil Kaseya 2 Addin.