Launch the game from inside the Ubisoft connect launcher works for me. Give it a try

I climb via the roof & have no way to get out now.....sigh., Not sure if it is a bug, all the doors are shut & the roof is inaccessible.

Wasted 30mins at least.

Edit; okay, managed to get out from the roof. You have to climb at a wired (to me) position near wall.

Opening Ubisoft Connect,
Log in,
Update the game,
& run from there worked for me.

Hope this helped someone.

I have the same issue. Game cannot start. Said service unavailable. Works fine with other epic games.