I recently upgraded from 15 to 16 version (on Windows 7) and use FileMaker server 16 too (on Windows Server), with ESS connections to Microsoft SQL Server 2012 with the last Microsoft driver supported by FileMaker. Everything run @64bit. Here are some failures I didn't have before, under 15 version: a) random errors when retrieving data from ESS connections; b) different behaviour of text functions like Middle() and Position(), that don't count CRLF carachters in text files, when before they counted them as ordinary carachters. Because of that, I was forced to uninstall FileMaker 16 version and go back to 15, where everything seems ok, until now. Hope Filemaker will fix this very soon!