We are deeply sorry for the inconvenience. You might have experienced a temporary downtime of the Telerik Platform services that has been reported to affect a minority of our users. The issue should now be resolved and you should be able to access your projects and data.
Furthermore, you should be able to update to AppBuilder 2.1.1
which has just been released and although a maintenance release, provides a few exciting features and many bug fixes.
Don't hesitate to let us know if you're still having troubles using AppBuilder.
Share what you think about AppBuilder and Telerik Platform with us in our feedback portal, so we can become even better!