It may be time to visit the Files area in your Canvas courses. Check to see if there are any unused files that can be either deleted or downloaded and stored on your computer or a portable hard drive. Having a clean and well-organized Files area is very satisfying and makes troubleshooting unlinked file errors much easier.
Another reason for clearing out unused files is that Ally, our course accessibility checker looks at every file in your Files area and gives each one an accessibility score. Instead of spending time fixing inactive files to make them accessible, remove them from the course. This will immediately improve your overall accessibility score and save you a lot of time fixing files that you are not actively using in your course.
One more suggestion, before you delete or download files, request a new source course, and move your entire course content into the new source course. This acts as a backup for your entire course and preserves all content and files. Source courses do not go away and are easily accessed for copying content.