There is a server in my development environment I upgraded it to Windows 2012 R2 Standard from Windows 2008 R2 Standard. After the upgrade, the Windows explorer couldn't run, so at the logon screen it is black with a mouse cursor. Pressing Ctr+Alt+Del the task manager can be brought up, then running explorer nothing appear but if check on 'create this task with administrative privilege' to run explorer, it ran. However, all the icons in start menu show black icons, no picture. That was on Windows 2012 R2.

I proceeded further, upgrade it to Windows 2019 Standard. The upgrade was fast, but this time the problem is when I clicked on Start, nothing appear. Further investigations, I found Search, Settings are not working - nothing appear when clicked. When right-click the Start button, the context menu appeared but within the context menu these are the items that when clicked nothing appear - App and Features, Power Options, System, Device Manager, Network Connection, Settings, Search.

In Eventviewer, applications, these 3 Applicator Error Event ID 1000 constantly appear:
Faulting application name: ShellExperienceHost.exe, version: 10.0.17763.1075, time stamp: 0x5e4f9944
Faulting module name: twinapi.appcore.dll, version: 10.0.17763.1075, time stamp: 0x4a83aa8c
Exception code: 0xc0000409
Fault offset: 0x0000000000095cc7
Faulting process id: 0x1db8
Faulting application start time: 0x01d72c1ffb26e8f1
Faulting application path: C:\Windows\SystemApps\ShellExperienceHost_cw5n1h2txyewy\ShellExperienceHost.exe
Faulting module path: C:\Windows\System32\twinapi.appcore.dll
Report Id: aeaa0fc1-a905-4cb3-810a-5f2c8f08691c
Faulting package full name: Microsoft.Windows.ShellExperienceHost_10.0.17763.1_neutral_neutral_cw5n1h2txyewy
Faulting package-relative application ID: App

Faulting application name: SystemSettings.exe, version: 10.0.17763.1, time stamp: 0x9d9d9332
Faulting module name: twinapi.appcore.dll, version: 10.0.17763.1075, time stamp: 0x4a83aa8c
Exception code: 0xc0000409
Fault offset: 0x0000000000095cc7
Faulting process id: 0x4dc
Faulting application start time: 0x01d72c200df76927
Faulting application path: C:\Windows\ImmersiveControlPanel\SystemSettings.exe
Faulting module path: C:\WINDOWS\SYSTEM32\twinapi.appcore.dll
Report Id: 76d4395e-1065-462d-8bf5-231643ac30b8
Faulting package full name: windows.immersivecontrolpanel_10.0.2.1000_neutral_neutral_cw5n1h2txyewy
Faulting package-relative application ID: microsoft.windows.immersivecontrolpanel

Faulting application name: SearchUI.exe, version: 10.0.17763.1075, time stamp: 0x5e4f64b8
Faulting module name: twinapi.appcore.dll, version: 10.0.17763.1075, time stamp: 0x4a83aa8c
Exception code: 0xc0000409
Fault offset: 0x0000000000095cc7
Faulting process id: 0x754
Faulting application start time: 0x01d72c1fcd7c9fb9
Faulting application path: C:\Windows\SystemApps\Microsoft.Windows.Cortana_cw5n1h2txyewy\SearchUI.exe
Faulting module path: C:\Windows\System32\twinapi.appcore.dll
Report Id: 3f55dc34-eaf0-4fd7-81ff-4650cbe25e3b
Faulting package full name: Microsoft.Windows.Cortana_1.11.6.17763_neutral_neutral_cw5n1h2txyewy
Faulting package-relative application ID: CortanaUI

Any idea what went wrong?

In place upgrades are never recommended. Better option is to clean install the operating system and migrate roles over to it. I'd start by checking here and with manufacturer about support for Server 2019.
https://www.windowsservercatalog.com/

--please don't forget to Accept as answer if the reply is helpful--

Firstly, after you performed an upgrade, I suggest that you could check for update to install new security updates.
It will update your system files. Because it seems to be related to your system files damaged. Then check if it works.
Then create a new user account to log on. It could make sure your user profile work file.
Hope this helps and please help to accept as Answer if the response is useful.
Best Regards,

I'd start by checking here and with manufacturer about support for Server 2019.
https://www.windowsservercatalog.com/

then try a clean fully patched installation.

--please don't forget to Accept as answer if the reply is helpful--

The server is IBM x3550 M4 7914OZN Intel Xeon E5-2630 2301 Mzh
It is certified for Windows Server 2008, 2008 R2, 2012, 2012 R2.
However the problem I am facing here is not related to hardware compatibility because before this I already did a disk2vhd and ran it in Hyper-V with exactly the problems I described above. So, I am very certain nothing to do with the hardware.

The applications installed on this machine and all of them are running fine after the upgrade: Acronis Backup 11.5, BigFix agent 9.5.15, IBM WebSphere Eclipse Platform 3.0.1, IBM WebSphere MQ, Java 8u144, Java8u112, McAfee Agent 5.7.1.116, MS SQL 2005, MS VC++ 2005/2008/2010, SafeNet ProtectToolkit C 5.2.0. There is also an in-house developed software installed.