Error loading type library/DLL” (Error code: 0x80029c4a) when using Windows Defender

Question

Since installing Windows 10 Fall Creators Update (version 1709), Windows Defender returns an error message while using the interface:

“Error loading type library/DLL.”  It also provides an error code:  0x80029c4a.

Answer 1

This error can occur in Windows 10 Fall Creators Update (version 1709) if you are using a shortcut to open Windows Defender, and that shortcut was created while using Windows 10 version 1703.

Windows Defender Antivirus had an updated experience that shipped with Windows 10 Creators Update (version 1703), which was designed to be easier to use and provide a comprehensive security experience.  However, the old UI from version 1703 is no longer supported in version 1709.  

To resolve the error, we recommend you delete any previous shortcuts you were using launch Windows Defender and create a new shortcut within Windows 10 version 1709.

If you are still having problems with Windows Defender, you can also use the Feedback Hub app as a great way to provide feedback directly to the product team.  You can check out this article for steps to Send feedback to Microsoft with the Feedback Hub app.

Answer 2

there's got to be a way to fix it

Indeed there is, BattedGiraffe73 – and the way was just provided by Community Moderator bhringer in this thread:

https://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_scanning-windows_10/windows-defender/5df86e81-a137-434f-a4cc-2d7672d753d7

Updated instructions for a shortcut to the classic Windows Defender UI (12/6/2017):

Right-click on the desktop and select New > Shortcut.

Then copy and paste this line for the “location”:

"C:\Program Files\Windows Defender\MSASCui.exe"

Now right-click on the shortcut and choose “Run as administrator”.

Then to automatically run as administrator:

Right-click on the shortcut and select Properties > Advanced > Run as administrator (check).

To run as administrator with a single click:

Unpin the old shortcut from the taskbar 

Right-click on the desktop shortcut and select Pin to taskbar.

That should give you access to the History tab.

[Edited 10/29/2017]

You can also start a fully functional instance of the classic Windows Defender interface from the search box – just type “MSASCui.exe”, right-click on the entry for the app, and “Run as administrator”.

[end Edit]

I just quarantined the eicar.com test file here and then “allowed” it in order to confirm that running the old Defender interface as administrator does indeed solve the access issue with the History tab. So this fix is something that people can use until Microsoft gets the issue sorted out (if that’s actually their intention). Of course getting familiar with the new Windows Defender Security Center app is still a must-do for all Windows 10 users:

GreginMich

Answer 3

Here’s the original source of this information, but I’m glad that the Microsoft forum people had so much confidence in my work that they were willing to create their own question/answer thread for the issue:

https://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_scanning-windows_10/windows-defender/5df86e81-a137-434f-a4cc-2d7672d753d7 

https://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_start-windows_10/windows-defender-error-loading-type-librarydll/f9f1dc48-ccaa-4702-b7b0-c60b9c07dba3 

Maybe they’ll now be willing to open up a ticket with the Feedback Hub, since my bug report there seems to be languishing.

Also note that since the Windows Defender Security Center app was already included in Version 1703, there won’t be any issue for shortcuts created in that version – this is only an issue for shortcuts created prior to Version 1703:

https://docs.microsoft.com/en-us/windows/threat-protection/windows-defender-antivirus/windows-defender-security-center-antivirus

The last version of Windows 10 that “supported” the old Defender interface (MSASCui.exe) was actually 1607.

[Edit on 10/28/2017]

Also, please see my recent reply to Microsoft employee Jairit Be in this thread:

https://answers.microsoft.com/en-us/protect/forum/protect_defender-protect_scanning-windows_10/windows-defender-not-showing-the-quarantined-files/efe43fe6-8f87-4d9b-a3dc-1bd13294f9c7?page=2#LastReply

[end Edit]

GreginMich

Answer 4

Once Version 1709 is installed, you’ll be able to reproduce this bug for yourself, Rob. When you open the old Defender interface (MSASCui.exe), and then click on the History tab, this is what you get:

I agree that redundancy should always be a consideration with anything that relates to security; and that having a “backup” Defender interface would always be a good thing, especially when we’re transitioning to a new interface – and that’s the reason why I filed my bug report for this issue.   

Shortcuts are a fact of life, and the problem here isn’t that people have intentionally created a shortcut to an old interface; it’s just that the shortcuts that were created when the old Defender interface was still current now need to be updated because of this bug.

GreginMich

Answer 5

It's not a bug Greg, it's a legacy component that simply hasn't been removed.  I personally wonder if they'll ever remove it, since it's still required for the Windows 8.1 version of Defender and so may continue to exist in the future as part of the complete package, though I'd think they'd have enough differences between these that the ability to compile for the specific Windows version must exist.

My bet would be that they've simply left it as a "backup" module until such time as they're certain the Windows Defender Security Center provides all of the necessary components.  In fact, I would bet they're still monitoring the older interface with telemetry to see how many people actually use portions of it rather than the new one.

Out of curiosity, do you remember any recommendation by Microsoft itself (e.g. not members of this forum or contractors) that anyone create a shortcut to the older interface, because I don't.

Rob