As a disclaimer please always make sure you have secured your 24 word seed phrase before making any drastic system changes, primarily if you skip the step to reflash your MicroSD card (where you don’t lose any data) and instead skip to reformatting your storage drive then you would lose all your data (all data is stored on the storage drive and will result in a clean install)
This error is the result of several issues usually occurring on Raspberry Pi 4 devices and related to the MicroSD card and/or a read/write issue with the installed storage drive.
This is for when you receive this screen specifically:
It can be caused by a failing MicroSD or a storage device that has not been formatted correctly in ext4, has become corrupted, or simply had any data on it prior to attempting a new installation.
The most reliable fix for this issue if you are on the Raspberry Pi 4 platform is to reflash your MicroSD card. If you have another one you can swap in, please try another card as well
SSH and run this command to safely shutdown: sudo shutdown
Unplug power and reflash your MicroSD card, then when complete, plug in your power last and wait ~5 minutes
For reference, reflashing will not result in any data loss because all user data is stored on your external storage drive (SSD or HDD).
To reflash your MicroSD card, follow the steps on our website under “Install on a Rasberry Pi 4.”
If it is your first time setting up Umbrel, and you don’t have any data on it yet please try reformatting your storage device again and make sure all partitions are completely clear- this is also a common cause if you already had a prior installation or any data on your drive and are trying to setup like new once more. You can delete all partitions and format in any default format file type, upon a successful Umbrel installation- during the Umbrel setup it will then automatically format again in the correct ext4.
For Windows you can use a program called AOMEI partition assistant to detect and manage ext4 disks and format them. On Mac there is a program suite from Paragon software you can also use to manage ext4 disks, to avoid the hassle of manually mounting and wiping an ext4 drive. This process is detailed in another guide here.
If after a reflash or this problem persists on a different Linux installation please reach out to us so we can track and resolve these issues for you to avoid having to delete and reinstall. You can always connect directly with our team using the chat icon 
located at the bottom right of Umbrel.com or make a post in our Help & Support Telegram Channel
When reaching out let us know when this issue began and provide us your debug logs for review so we can investigate and get you back up and running.
Following the instructions in How to SSH into Umbrel on a Raspberry Pi and Generating Troubleshooting Logs