Are you absolutely certain your application is OpenServer or is it only OpenClient?
Older releases (pre-15.x) of the the OpenClient SDK did refer to some OpenServer libraries. These libraries were removed in SDK 15+ releases. A 'copylibs.bat'/'linklibs' script was provided at the time to allow older 12.x OpenClient code to still run with 15.x libraries (using symlinks or copies of the 15.x libraries to match the 12.x names), but the suggestion was and is to always re-compile older OpenClient code with the new headers to avoid this workaround.
If your application is actually OpenClient, then you must re-compile and link your code with the proper headers and avoid the references to the server library.
If however you are actually compiling an OpenServer application, then you must purchase the OpenServer license for your new platform.
Chris