The winforms .NET Core app cannot run when targeting .NET Core 5.0

[Amy-Li02-zz]

• .NET Core Version: .NET Core SDK 5.0.100 - alpha1 5.0.100.14915
• Have you experienced this same bug with .NET Framework?: No

More info:

1. WPF .NET Core app also cannot run when targeting .NET Core 5.0.
2. Console .NET Core app can run when targeting .NET Core 5.0.

Minimal repro:

1. Install .NET core 5.0 SDK from: https://github.com/dotnet/core-sdk.
2. Create a Windows Forms .NET Core App and target net core 5.0.
3. Press F5.

Actual behavior:
The WinForms .NET core app cannot run.

Expected behavior:
The WinForms .NET core app can run successfully.

Error log:
ReproSteps_1571820778007.zip

[Amy-Li02-zz]

Verified with .NET Core SDK 5.0.100.15374 build, the winforms .NET Core app can run successfully, so close this issue.