How can I open new files in older versions of Adobe programs? Adobe does actually support backward compatibility.
The caveat is that it can only be done in single version iterations from within each version of the software.
You can only save a file backward to CC 2015.3 from within CC 2017. To save the file backward any further, you will need to do so from within CC 2015.3 and so on.
File > Save As > Save a Copy As > CC <version #>
- File > Save As
- In Illustrator Options, under Version drop down menu, select Illustrator <version #>
This is automated as long as files have Maximize Compatibility checked when saving. However it will result in larger file sizes.