Gen ASP.NET client calling .NET Server shows blank page instead of login

Products

• Gen
• Gen - Run Time Distributed

Issue/Introduction

Gen 8.6 ASP.NET clients to .NET Servers.
Adding new server (and client) to existing application for deployment to IIS.
Initially encountered this error when using the client:

Function: TCPIPConnection::openSocket]: failed trying to create/connect socket.The requested address is not valid in its context

After uninstalling the assembled .msi file and reinstalling it the connection error was resolved but when loading the client login page it only shows a blank page instead of the expected login page. No errors are visible.

Environment

Gen 8.6 .NET C# client/server application

Cause

The user found duplicate database connection strings in the <application_name>\bin\application.config file for the servers.
When the client started it called the server before displaying a page and the server database connection was failing. However no error was visible on the client side.

Resolution

Corrected the <application_name>\bin\application.config file.

Additional Information

The Build Tool assemble step for .NET has a tab "DataSources" where the Server Connection String for the database is entered and that is what is placed into the application.config file inside the MSI file. It is therefore strange that 2 entries were found in that file unless there is some manual process being used to modify the file as well.
Support did test manual edit of Gen sample model application.config file to have duplicate connectionString entries for GENDB and a client dialog box was displayed with "TIRM165E: An error was encountered on the server. The entry 'GENDB' has already been added. (C:\Program Files (x86)\Broadcom\sample\bin\Application.Config line 3)". A server side trace file will also show the same error (see below)

Support troubleshooting suggestions for tracing this type of problem

On the client side edit the <application_name>\web.config file and change cmidebug from 0 to -1 to generate a trace file. 
That is per "Trace Generated Applications" on this doc. page: Gen™ 8.6 > Distributed Processing > Working With ASP .NET > Building an ASP.NET Web Client Application
From Support testing the trace*.out file is not created in directory %USERPROFILE%\AppData\Local\CA\Gen86\logs\net suggested by the above doc. page but is instead created in directory <application_name>\log.
The client side trace file can be useful to determine root cause of server connection related issues like the original TCP error encountered and will show the commcfg values being used from the commcfg.txt file. This trace also starts earlier compared to when setting CMIDEBUG=ON in the commcfg.txt file.

On the server side edit the <application_name>\bin\application.config file and change cmidebug from 0 to -1 to generate a trace file which is also created in directory <application_name>\log. (Gen™ 8.6 > Distributed Processing > Working with .NET Servers > Logging)