If you have a user with a bunch of apps to update in the iOS App Store, but tapping the Update button opens the app instead of updating the app, check to make sure her iOS is up to date.

For example, if you have a lot of pending app updates and are still on iOS 7, you may not be able to update them until you upgrade to iOS 8. I’m not sure why Apple doesn’t tell you that (there should be an error message “You cannot update this app until you upgrade to the latest version of iOS” with a link to Settings to do the iOS upgrade) instead of just opening the app.

Just a note in case anyone else has users with this issue (and a grayed-out Update All button).