You would intuitively force close the App Store app to fix the issue. However, as Twitter user Zachary Drayer points out there is a much more elegant way to fix the problem.
All you need to do is tap on any of the tab bar icons at the bottom such as Featured, Top Charts or Updates in the App Store app, multiple times to force refresh the App Store.
You will notice that after tapping on one of the icons around 10 times, it results in refreshing the App Store app. It should fix the annoying issue where the App Store is telling you the app needs an update, but you can’t.
It is always great to come across tips and tricks that you don’t know. This trick also works in the iTunes Store and the iBook Store apps. You can also use this trick to check for new app updates rather than force closing the App Store app and relaunching it.