Installing a new version of macOS—such as Apple’s new macOS 10.13 High Sierra—is a big deal for your Mac. Metaphorically speaking, you are swapping out part of its brain. And with High Sierra, the installer may also be converting your startup drive’s file system to APFS—that’s a huge under-the-hood change! Making a backup before you upgrade is always a good idea, of course, but it’s easy to overlook the simple step of running the First Aid feature of Apple’s Disk Utility. First Aid can either confirm that your startup drive is healthy or, if it finds problems, try to repair them. To begin, launch Disk Utility, which you can find in the Utilities folder inside your Applications folder. In Disk Utility, select your drive on the left and click First Aid in the toolbar. Follow the prompts, and wait a few minutes for the check (and any necessary repairs) to finish. If you see a check mark in a green circle when the scan is done, all is well. Otherwise, follow any directions suggested by Disk Utility or contact us for assistance.