How to Fix the 0x800705b4 Windows Update Error

The Window 0x800705b4 error is effectively a problem with the Windows Update service that is unable to complete its task for some reason.

Keeping Windows updated is of paramount importance if you want to retain the latest features and, more importantly, the latest security patches. But sometimes Windows update errors get in your way and oftentimes they're the fault of Windows itself too.

What is the 0x800705b4 Error?

The 0x800705b4 Windows update error is an odd one. It typically appears when you attempt to complete a Windows update, or if the update scheduler activates at its alotted time.

There are several causes for it, namely problems with the service itself, and Windows Defender getting in the way. But narrowing down the root of your 0x800705b4 error involves trying various fixes, so we won't focus on the symptoms, just the potential cure.

How to Fix This Windows 10 Update Error

There are a few different things we can try to get Windows 10 updating properly again. Some are a little more hands-on than others, but none are overly complicated. We'll start with the easiest and most likely to be successful and work our way through from there.

After each fix attempt, we'd suggest rebooting your system and trying to update Windows again.

Run an antivirus scan. It might seem unlikely, but Windows errors can sometimes be placed at the feet of malicious software like viruses and malware. Running a scan can help fix that. If you don't already have one, you can install an antivirus application and then run it to ensure there isn't anything nefarious lurking in the shadows.
Run Windows Update Troubleshooter. Windows' troubleshooters are a great way to try to figure out what's wrong with your system. Even if they don't fix it, they might be able to point you in the right direction.
Reset Windows Update. It might be that a certain component of the Windows Update process has broken down for some reason. There is an automated script you can run (you can download the script from Microsoft). If you'd prefer, you can also run the update process manually.
Run a System File Checker scan. Another way to potentially fix this update problem is to perform a file checker scan. It can be triggered with one simple command: sfc/scannow. There are also a few other sfc commands worth learning if you're interested in the versatility of this tool.
Run a DISM scan. You can also try running a deployment image servicing and management (DISM) scan. This is less likely to fix the issue than the above methods, but it's easy to do and can cover a few potential problems—Windows update errors included.
Change Windows Update Settings. It may be that an unnecessary component of Windows in the update is preventing it from downloading. Only focusing on important Windows elements might get around that. Just remember, if you turn Windows Automatic Updates off, be sure to turn them back on again once your issue is resolved so you don't miss any important security updates.
Disable your antivirus. This should only be attempted if you've tried everything else. Keep in mind this should only a temporary measure. You must re-enable your antivirus after the update has completed, as it's paramount to staying safe online.

If you're running Avast Antivirus, you can disable it temporarily (or permanently, if you choose).
If you're running AVG, it's also pretty easy to disable your antivirus.
Malwarebytes users can use this first-party guide to disable its real-time protection.
Norton Antivirus can be temporarily or permanently disabled if you follow these steps.
For McAfee users, disabling your antivirus should be just as easy.

If you're using another antivirus client, check the official site to see if there's a guide on how to do it. Alternatively, check the taskbar. You can likely disable the client from there.

If you do disable your antivirus temporarily, make sure to re-enable it later to stay protected.