Reflection Desktop (including Pro, for X, for IBM, or for UNIX and OpenVMS) 16.0 or higher
Unexpected errors can occur when opening a new Host session file (RD3X, RD5X, RDOX) on an older version of Reflection Desktop. For example, if the Host session file is originally created and saved in Reflection Desktop 16.1 and then an attempt to made to open this file in Reflection Desktop 16.0, unexpected errors or failures may occur.
Reflection Desktop Host session files are always forward-compatible with newer releases, but not necessarily backward-compatible with older releases. It is recommended that you always create and save Reflection Desktop Host sessions in the version of the product they will be run against or only use Reflection Desktop Host sessions from older versions in newer versions.
As new features and functionality are added to the Reflection Desktop software, new configuration options and settings are also added to the Host session documents and these settings may not be recognized or handled properly in older versions of Reflection Desktop. Forward compatibility or moving Host session documents forward to newer Reflection versions is always tested and supported, but running Host sessions created in newer versions of Reflection Desktop (backward compatibility) is not always supported when these Host sessions are run against older versions of the product. It is recommended that Host session files always be moved forward to new release and not backward to older releases, as your mileage may vary.
An example of this sort of issue is seen in article https://support.microfocus.com/kb/doc.php?id=7023413.