Build project failed after upgraded from .NET7 to .NET 8

[phuocminh6464]

Hi everyone,
My solution has 3 project (all of them use .NET 7): project 1 is .NET library, project 2 is a windows app, and project 3 is also window app. Project 3 IS the main app and it included 2 remain projects. Now, I want to use .NET Upgrade Assistant to upgrade .NET7 to .NET8.

I start with project 1 first, it upgraded and build succeeded. Next, project 2 is upgraded but build with 1 failed. And finally the main app is upgraded too but build with 2 failed and no error in Error List tab.

After that I cleaned and compiled the main app got 1 succeeded, 2 failed. When I run source code, the below popup is appear. How to fix this?