I tried so tirelessly to enter today's contest since 5 minutes before the start of contest but sadly failed. It just didn't open with 1200 error. I had to give up after 20 minutes. I feel glad now that I hadn't registered to contest before.
This is not the first time I saw this, I saw this last week contest as well but then it opened after couple of minutes.
Leetcode engineers please work on scaling to handle website traffic.