Problem: Image module upgrade fails (update function fails, images missing, etc.)

Solution: Even though its status will show as green on the Update Status log page, version 5.x-1.9 of the Image module will not upgrade to Drupal 6.x

To upgrade to Drupal 6.x you must be running the 5.x2.x version of Image module (currently version 5.x-2.0-alpha3) for an upgrade to Acquia Drupal to succeed.