Cannot run 64 bit Intraweb app on older server (2012R2) since Delphi 11.3

[rudyPos]

This may be a combination of Embarcadero Technologies Delphi and Intraweb

iw 15.x

A) I have a web server application compiled as WIN64 that was running successfully on Server 2012R2
B) Delphi was updated to 11.3 from 11.2. - web server application recompiled and runs successfully tested
on Win 10 (my Delphi PC).
C) copy updated exe compiled under 11.3 to target server - Application does not start 'app crash'.
D) copy app in 11.3 as 32 bit app = runs on Server 2012R2
E) a non Intraweb app in 11.3 as 64 bit does RUN on Server 2012R2.

Any ideas? The only setting in project options I have modified is PE header info, bu this made no difference,
and did not need to be changed for the non-IW app.

Thanks in advance