Windows Defender Error loading type library/DLL, 0x80029c4a
You must know that what Microsoft used to call Windows Defender is now known as Windows Security. The error code seems to be occurring, according to forum users, to those who are trying to launch Windows Defender but using an old shortcut that was for Windows Defender Security Center. Let’s be specific. When you use the old shortcut, you are launching an older version which is still supported or available on your computer. This file is not available anymore in Windows 10 v1903. There are two ways to fix it:
1] Run MSASCui.exe with admin privileges
Navigate to the C:\Program Files\Windows Defender directory.Right-click on the MSASCui.exe and select Run as Administrator.
It will launch the Windows Defender Security Center, and you should be able to manage your quarantined list. When you upgrade to the new version of Windows, this shortcut will stop working.
2] Use the new Windows Security
Type Windows Security in the StartWhen it appears, drag it to the desktop or right-click and add to taskbar.Now when you launch it, it will open the new interface, and it will work properly without any error.
This bug was identified by Microsoft as well, and one of the engineers left a comment in the Feedback Hub. It said: We hope the solutions worked for you, and you were able to use it again. You should upgrade your Windows 10 to the latest available version or switch to the new interface and get rid of this error.