You may recently have some problems with installing macOS Catalina. Perhaps the upgrade took too long to load – a lot more than it should have. If you really encountered these problems, then something is wrong with the installation process. You might want to leave your Mac overnight in order to see if it would self-correct, but you will probably have to intercede on your device.
If your device shows you the “Setting up your Mac” screen – it should appear a short time after the App Store Catalina finished the download – you already have one solution to make it work on your Mac. You will need to reset it. In order to do that, hold down the power button of the device until it turns off. Then turn it back on.
As MacRumors says, after the device gets the screen with “Setting Up Your Mac…”, the macOS Catalina installation is complete. However, they do not recommend you to restart the device right away, but also do not let it run like that. If the screen sits like that for more than half an hour, shut the device down. This installation takes some time, so don’t restart it before the setup screen appears. However, according to numerous reports, resetting it this way is actually a safe way of getting your device running again.
This is the first trick to try when you are troubleshooting the issues with your Mac. You should do it, especially if the installation process frozen. It’s the best one when it comes to Catalina. But be careful, if you do this, you can lose some of your data, or encounter any other problem which usually appears when you power down your system.