Oh shit, son, 4chan is down! The domain's been hijacked. Thanks a lot, Network fucking Solutions! You guys are shit and ass, and cock, and you are awful at everything you do.
Edit: I added a full item on the details to the ED article on Brb, Compromised.tl:dr; someone stole 4chan.
The archival system broke because there's no sanity checking; it expects 4chan to return a thread, return a 404, or return nothing (in the instance of a DDoS). Since 4chan has a page but it's not a thread, the most recent archived threads are wiped out. Baw.