A forum post on the official League of Legends website shows that some users in the UK are having troubles updating their game due to the anti-porn filter their government put in place.

Apparently, a few files included in the update process contain the word "sex" and are thus not able to obtain the files while updating. I kid you not.
VarusExpirationTimer.luaobj

and

XerathMageChainsExtended.luaobj

ISPs are blocking any URLs that contain specific words that typically lead to porn. How do you fix it? Either get a friend that doesn't have this problem to share their League of Legends folder with you after every update, or contact your ISP to remove the filter on your account.

This is just another in a long string of legitimate services and sites that are being blocked by the UK's anti-porn crusade.