Opening Scenario: You’ve just received a beautiful Adobe InDesign package from a freelance designer. You double-click the .indd file, and your screen freezes. A cold, gray error message appears: “This file was created in a newer version of Adobe InDesign and cannot be opened.”
The most efficient conversion is the one you never have to perform. Adopt a collaborative workflow that prioritizes backward compatibility from the start: how to convert indesign file to older version
If you do not have access to the newer version of InDesign that created the file, third-party tools can bridge the gap: The Ultimate Guide: How to Convert an InDesign