The latest update caused a lot of troubles to many users, but don't worry, a fix is on the way! Microsoft is currently certifying a new version of the app that will fix crash on launch and the frequent crashes when switching between chats.
If you're using Unigram direct, you can update immediately by clicking here, if you are a Microsoft Store user you have to hold on a few more hours!
Here's a sneak peek of what you'll find in this update.