To open an InDesign document in the previous version, first export it to IDML (InDesign Markup Language) or INX (InDesign Interchange format), depending on the version of InDesign it was created in.
Make sure that the version of InDesign used to open the IDML or INX file has all available updates installed. Otherwise, InDesign returns an error about missing plug-ins when you try to open the file. You can obtain compatibility plug-ins by choosing Help > Updates and following the prompts. You can also install plug-ins from the Adobe website. Visit the Product updates page, and choose InDesign from the product list.
Note: Content created using features specific to your version of InDesign are sometimes modified or omitted when you open the document in the previous version. Carefully review any document opened in a previous version.