I have new Macs that run High Sierra, but I also have a few older Macs that I keep on Mavericks. These older machines run Mavericks well, plus I like the look and feel. I imagine that most other people who are still running Mavericks feel the same way. There's one problem, though. When you open Pages, Keynote or Numbers, you get a pop-up saying "A free Pages update is available. Install the latest version of OS X, then visit the Mac App Store to download the latest version of Pages." This message appears once per day when you open one of the iWork apps. It isn't tied to your system preferences for automatic updates or anything like that - the iWork apps just pop up this message because it was hard-coded into the last versions Apple made for Mavericks. This message has annoyed me for some time, but I've finally figured out how to turn it off. Apple have programmed these messages to show up once per day. Somewhere deep in iWork's Application Support folder, there's a plist file that stores the next time the popup is due to appear. When you open an iWork app, it checks the date saved in this field. If it's in the past, it shows the message and changes this date to 24 hours in the future. All you have to do is edit the plist file and change the "show this popup again" date to something ridiculously far in the future. Here's how you do it: Download PrefsEditor. It's an app for editing plist files, and it's free. If you have Xcode installed, you can use that. But PrefsEditor shows you a list of all the Plist files you have installed - you don't have to go searching through your Application Support folder to find the files. Open PrefsEditor and choose com.apple.iWork.Pages.plist from the list of plist files. A list of all the preferences in this plist file appears. You'll see a folder called TSAAUNPersistedState. Click the arrow to open it. Inside, you'll see a setting called nextAlertPresentationDate. Change this to something far in the future. I used 2030-12-31 23:00:00. Now, save the file with Cmd + S. You'll want to go to File then Open Bundle ID in the menu and do the same for com.apple.iWork.Numbers.plist and com.apple.iWork.Keynote.plist.