If Windows 10 2004 aka May 2020 Update isn’t offered for your device, forcing the upgrade through Media Creation Tool may result in OS install failure and your PC will be rolled back to a state where you’re before installing Windows 10.
Windows 10 May 2020 Update is available for Windows 1903 and 1909 versions. Seekers running these versions, can manually check for updates and install the Feature Update if offered.

Windows 10 feature update is currently being also rolling out to systems that are reaching the end of service.
If you check for updates, If your device has no compatibility problems, Windows 10 2004 will be offered and you can install it.
If Windows Update shows the message “Windows 10 May 2020 update is on the way“, then you’ve to wait as your device isn’t compatible.
If you try to force install the Windows 10 update on your device through the Media Creation Tool, the installation may stop in the middle and your device will be rolled back to the previous state
A user on Reddit reported he couldn’t able to install 2004 update with Media Creation tool and is getting the following error:
“We couldn’t install Windows 10.
We’ve set your PC back to the way it was right before you started installing Windows 10.
0xC1900101-0x20017.
The installation failed in the Safe_OS Phase with an error during Boot Operation”.
Here 0xc1900101 is a rollback code and according to Windows 10 Upgrade error code help page, the cause for the error is this:
“A driver has been caused by an illegal operation. Windows was not able to migrate the driver, resulting in the rollback of the operating system.”
This issue can be caused by drivers or non -Microsoft Disk encryption software.
You can find the problematic drivers for this in setuperr.log and setupact.log files in the %Windir%Panther directory.
Windows 10 2004 has a lot of known issues and some of the issues are not acknowledged by Microsoft.
One user in the thread noted uninstalling overclocking software helped him to overcome the issue.
Related articles:
Windows update is now showing Windows 10 2004 “isn’t quite ready” banner on Some devices
OneDrive is blocking Windows 10 2004 installation for some devices
Microsoft blocking Windows 10 2004 upgrade with “Your PC Settings aren’t supported” error
Microsoft Investigates Storage Spaces issue in Windows 10 2004