Yesterday I was trying to update my Kindle store app on my Windows 10 PC.
Unfortunately, Windows has decided that I should fail, throwing the 0x803f7000 error code on me.
Simply put, the cause for this error is a corruption in the local store cache, and the solution for this error,
is to reset the store cache. Luckily resetting the store cache is an easy task to complete.
Run wsreset as admin.
Click on the search icon next to the start menu icon, type wsreset, then right click the first result and select Run as administrator.
A CMD window will appear, followed by the store window.
Wait for the CMD window to close, then close the store app, wait for 5 seconds and open the store again.
You should now be able to update / install apps without any problems.