I have an application that is being migrated from server 2008 to server 2016.  The files including the web.config have been copied from one server to the other.  I have converted the application in IIS and set the authentication.  A test html page was added to the project to verify the connection.  IT WORKS! The other pages .aspx in the project don't work.  The event viewer has the following entry.

Event code: 3005

Event message: An unhandled exception has occurred.

Event time: 12/14/2018 11:25:14 AM

Event time (UTC): 12/14/2018 7:25:14 PM

Event ID: 740c301e8c5648d881192a0d07e694f0

Event sequence: 35

Event occurrence: 1

Event detail code: 0

Exception information:

Exception type: FormatException

Exception message: Input string was not in a correct format.

at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)

at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)

at System.String.System.IConvertible.ToInt32(IFormatProvider provider)

at ASP.global_asax.Session_End(Object sender, EventArgs e)

Thread information:

Thread ID: 27

Is impersonating: False

Stack trace: at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)

at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)

at System.String.System.IConvertible.ToInt32(IFormatProvider provider)

at ASP.global_asax.Session_End(Object sender, EventArgs e)