Windows Defender 0x80070424 Error

I believe I have a fix for you if you haven't found one yet or reinstalled. I also had this same problem and was able to fix it fairly easy.

Actually I haven't been able to get it fixed yet. I've been using Microsoft Security Essentials currently which works very well but I still would love to get my Defender fixed.

Ok. First can you check if you have a windows defender service running by going to start, and search for services. Second check your registry for this key: H_KEY_LOCAL_MACHINE/System/CurrentControlSet/services/WinDefend. In the WinDefend folder there should be 3 subfolders labeled parameters, security and triggerinfo. Let me know if you have the windefend service running or these keys in your registry.

First and foremost, there is no Windows Defender Service listen in my services.msc. In my registry, I have ControlSet001 AND ControlSet002. Both those folders have a WinDefend folder and both those WinDefend folders only have the "parameters" subfolder, that's it.

You don't have a "CurrentControlSet" subfolder? It should be listed right below the two you named. If not try this anyhow just be sure to back up your registry before hand. After backing up merge this with your registry and reboot. Report any changes. windefend.reg

Geez, yeah I have a CurrentControlSet folder, sorry. It only has the parameters subfolder, just like the other ones though. I'll try running that windefend file, after backing up the registry of course. I'll let you know if it works.

It worked! Thank you so much. I have MSE running right now so Defender is disabled but, right after I disabled MSE, I was able to open Defender. You're a life saver thanks!!

Glad I could help! Thankfully you didn't have to format and go through all that hassel of reinstalling windows.

Apparently the malware can destroy some of the reg files. This also happened to my windows security center and I did a similar fix.

phw8558 said:

You don't have a "CurrentControlSet" subfolder? It should be listed right below the two you named. If not try this anyhow just be sure to back up your registry before hand. After backing up merge this with your registry and reboot. Report any changes. windefend.reg

After a lot of searching, I finally found this thread with the fix. The .REG file that phw8558 posted worked. And I have no clue how my Windows Defender got into this state in the first place. Well, thank you!!!

Thank you for this registry file! There's lots of advice online for this problem but none of it works. Finally found your file and it is fixed.

"Windows Defender specified service does not exist as an installed service. (Error Code: 0x80070424)"