I've just updated IntelliJ IDEA to version 2019.2 and after restart IDEA wasn't able to open any of my projects I've been working before.
During restart IDEA asked me to import configurations and I've selected the old from version 2019.1. But after start it showed me just Welcome screen with the list of all my projects, but when I've tried to open any of those projects Welcome screen blinked for a moment and then returned back, no project was opened. No error message was shown.
I've tried to remove my projects from the list and re-open them, but this didn't solved the problem. I have to go to each project directory and to remove .idea folder. After that I was able to open my projects again.
I have a lots of projects and to have to do this procedure for all of them is mildly saying very annoying.