I’ve been stumbling into this error a lot, trying to install some of the games I’ve purchased in Humble Bundles. It took a lot of digging around in various forums and lots of Google searches, but I finally came up with the resolution:
Unmount the external SD Card!!!
I know it makes no sense. I ignored a lot of suggestions from various posts because they didn’t make sense to me. But out of desperation one night, I decided to try it. And I’ll be damned if that didn’t work!
That might not be true in the future, but as of May 2015, it is the solution.
You’re welcome! 🙂