+* Missing characters in the output are now reported as errors. This leads
+ to error reports for documents that compiled without error before.
+ However, the error was always present but went undetected!
+
+* Documents using Times fonts and containing Greek characters may now fail
+ to compile under pdflatex for users of MikTeX due to an automatically
+ half-installed "grtimes" package. A workaround in LyX was removed as it
+ stands in the way of alternative approaches (see #6469).
+
+* With LuaTeX, LyX now uses polyglossia instead of babel if the language
+ package option "Automatic" is selected. In order to use babel, select
+ "Always babel" instead. This may be needed if a document uses code that
+ is specific to babel.
+
+* As usual, when opening and saving a document that was created by a previous
+ major version of LyX (in this case 2.1.x), the file format is changed to
+ the new file format (in this case 2.2.x). What is different starting with
+ 2.2.0 is that when we save a file that was not originally in the current LyX
+ format, we create a backup of the original file. We put it in the backup
+ directory, if one exists, otherwise in the directory the original file is
+ in. This is the same strategy as for normal backups. This backup file can be
+ helpful in case a bug in lyx2lyx caused data loss. For more information, see
+ #9554.