I logged in on the 21st to change a flight. I was able to get to my itinerary and choose the segment to change. When I clicked Continue, what United.com served up was an empty screen. I quit Safari, reopened and logged in again, to the same result.

Today, the 24th, I tried to log in, and got the same result as you--Sorry, something went wrong...

Not confidence inspiring, for an airline embarrassed by maintenance issues...