https://www.cnet.com/news/avengers-endgame-smashes-pre-sale-ticket-record-held-by-force-awakens/

Not all fans were able to just snap their fingers and get tickets. Movie theater chain AMC admitted in a tweet that its site had gone down. 

"We want everyone to be able to grab their Avengers: Endgame tickets, but it looks like we've gotten Thanos' snap," the site's official Twitter account said in a tweet.