I don't know what set up some people here have but I can assure you very few of the "fixes" describe here actually work. At least not on my ipad mini.
1. Unless you have an Apple laptop forget going to itunes to fix the problem, non of the solutions described work on an IBM compatible machine running windows. The option to right click and edit, delete or download an app doesn't exist on a window machine.
2. Syncing your laptop to your ipad doesn't fix the problem either. It might do for some people it most certainly didn't for me.
3. going into settings-general-etc is a waste of time, this resolution only works for an iphone, if you have an ipad don't waste your time looking the options just don't exist that are described in this thread.
4. closing down all the apps SHOULD work if the issue is that your memory space is maxed out, mine wasn't therefore this fix didn't work either.
The ONLY resolution here that I can confirm actually works is switching the ipad off and back on again.
I also suspect since this has now happened twice on the same ipad that it is related to the recent IOS8.0.2 update (the ipad in question is running IOS7) and that the updates could not finish installation because the ipad is running the out of date version of IOS. A possible fix therefore could also be to update to the latest version of IOS, a suggestion not even explored in the previous posts.