Whats the oldest existing bitcoin exchange around which never had problems like mt gox and is still around?
There are a lot of old exhange including poloniex bitfinex and coinbase there are also kraken too here in indonesia there is indodax and triv
And about the problem the key is that there is always a problem for centralized exchange but at some point they just improve their self like security patch and other but sometimes company like bittrex is cease to exists