'Error loading solution' error when trying to open any app

An 'Error loading solution' error started showing up whenever I try to open an existing app. Whether it's a .NET app or a non .NET app like a React app. It's trying to open the corresponding .idea file or folder. It's a show stopper because Rider doesn't load the app. I did a repair by installing it again and I still get the same issue. I just created a new React app and got the same message.