If you get an error message that reads:

IOError: I/O error

active process: image optimization

and includes information for the line, active page, ID version, and OS, it will likely add a note below the message that your files were successfully exported and the error occurred after export. 

The reason the error occurred after export is that the optimization process affects the images after they've been exported. 

Here are a few reasons that in5 wouldn't be able to optimize your images and how you can address each case:

  1. You're using a version of in5 prior to 3.8.0 on an M1 Apple silicon machine.
  2. You may not have admin rights which prevents the image optimization libraries from being able to overwrite the image files with the optimized image files.
    • Fix: Try running InDesign as administrator
      • For macOS:
      • For Windows:
        • Quit InDesign
        • Go to the Start menu and type InDesign in the Search or right-click on InDesign in the Taskbar
        • Right-click on Adobe InDesign 2022 in the either the results of the Search menu or in the menu that appears in the Taskbar
        • Select Run as administrator
  3. It's also possible that you may have an older copy of the image optimization libraries. If you (or your IT department) delete the directory that has the old image optimization libraries and reinstall the latest version of in5, then the new installation should use the updated image optimization libraries. Here are the steps:
    1. Delete this directory: [adobe indesign]/scripts/in5_v3
    2. Download and install the latest version of in5