So I am thinking this not a libpq issue, but a change in error reporting when the code was reorganized in 09.05.0100. I do not know the internals well enough to say anything more. Hopefully someone that does can fill in the blanks.
Thank for information.
I programmed in C 25 years ago. I'm using Visual Studio 2015 and C#. Should I start to research driver source code and odbc log to find out which method call fails ? Or is there better way ?