This blog is updated daily.
A general description is here.
Windows users should consult the WINDOWS section below for some profound changes including
• Support for 32-bit builds has been dropped.
• UTF-8 locales are used where available.
• The default locations for the R installation and personal library folder have been changed.
Thanks to Tomas Kalibera for months of work on the Windows port for this release.
The header ‘S.h’ which has been unsupported since Jan 2016 has been removed. Use ‘R.h’ instead.
(Not Windows.) ‘l10n_info()’ reports an additional element, the name of the encoding as reported by the OS (which may differ from the encoding part (if any) of the result from ‘Sys.getlocale("LC_CTYPE")’).