In this tutorial, learn how to fix Modern setup host has stopped working while trying to upgrade to Windows 10.
One of the issues many Windows users have reported that Modern Setup Host has stopped working error appeared when attempted to install the Windows 10 from their previous Windows edition.

If you are also facing this problem can go ahead with the following suggestions and overcome it:
Fix: “Modern Setup Host Has Stopped Working” While Upgrading To Windows 10
Method 1: Clear The Software Download Folder Contents
Step 1. Open the File Explorer, and navigate to:
C:\Windows\SoftwareDistribution\Download
Step 2. Then you delete everything in this folder Download.
Step 3. Next, you open administrative Command Prompt. To do that, right-click Start Button, select Command Prompt (Admin).
Step 4. In the Command Prompt window, type following command and tap Enter.
wuauclt.exe /updatenow
Step 5. Lastly, restart your system and check if the issue has resolved. If the problem still persists, you try to refer Method 2 below.
Method 2: Use Windows 10 Upgrade Assistant
You can also fix Windows 10 failure with Modern setup Host stopped working by using Windows 10 Upgrade Assistant. To do that, follow these simple steps:
Step 1. First of all, you need to download the Media Creation Tool Windows 10 for the same edition and architecture you’ve currently installed.
Step 2. Then launch the tool and choose to Upgrade This PC Now. You’ll see that it will stuck when creating installation media, so close the tool.
Step 3. Press Windows Key + R then paste this path into Run dialog box and tap Enter:
C:\$Windows.~WS\Sources\Windows\sources\setupprep.exe
Replace C: with your current system root drive.
Step 4. Your installation should begin and the upgrade should be able to finish.
Read more: Error 0xc000021a in Windows 10
Please do let us know if anything here helps you. If you have any other Windows and Office related issues you can check for the solution in my Windows fix section.