Poloniex, whose major investor is Tron CEO Justin Sun, published a tweet half an hour ago that the exchange is "in maintenance mode and unavailable."
The IT support teams of the company are investigating the issue and promise to keep the community updated.
All funds are safe, the tweet says, and the site will return to regular operating mode as soon as possible.
Many users in the comment threads are sharing their indignation, as many have open positions on Poloniex at the moment.
Earlier today, Bitcoin printed a new all-time high of $51,600, pulling altcoins along with it into the green.
On Dec. 5, 2020, Poloniex faced an outage due to a DDoS attack.