Windows defender - error code 0x800705b4

Question

I cannot turn on real-time protection - error code 0x800705b4. What is the problem and how do I fix it?

Answer 1

I cannot turn on real-time protection - error code 0x800705b4. What is the problem and how do I fix it?

Are you receiving other Windows Updates okay?  If not suggest you try the Windows Update Troubleshooter: https://support.microsoft.com/en-us/help/10164/fix-windows-update-errors

How long have you been using WD?

Sounds like you possibly ****have another security program installed or there may be remnants of such a program you previously used that are still on the computer and are interfering with Windows Defender.

https://support.microsoft.com/en-us/instantanswers/742778f2-6aad-4a8d-8f5d-db59cebc4f24/how-to-protect-your-windows-10-pc  Note the statement  "If you want to use Windows Defender Antivirus, uninstall all of your other antivirus programs and Windows Defender Antivirus will automatically turn on. You may be asked to restart your device."

On Windows 8.1/10 when a third party antimalware program (such as AVG, Avast, McAfee, Norton, etc) is installed the Windows Defender (WD) program is disabled by design to prevent potential software conflicts and performance issues.

If you wish to use WD on Win 8.1/10 you should ensure that any third party antimalware program that may be on the computer (or was previously on the computer – possibly before it was upgraded to Win 10) has been uninstalled and that no remnants remain. Note – most new computers included a trial version of various antivirus programs (McAfee, Norton, etc) depending on what the vendor/manufacturer wanted to be included on the computer.

It is recommended that you run the appropriate software removal tool for third party program(s) such as AVG, McAfee, Norton, etc that may have been on the computer and then reboot the computer. **List of anti-malware product removal tools**

WD should then be enabled though you might need to restart WD in Security Center.

For further information see the reply of quietman7 in http://answers.microsoft.com/en-us/protect/forum/protect\_defender-protect\_scanning/windows-defender/e994f94f-92d5-4d44-9721-79c2a686ce24

If you cannot resolve the issue follow the steps in Problems starting Windows Defender in Windows 8/8.1/10

And see Configure Windows Defender in Windows 8, 8.1 and 10 

http://www.groovypost.com/howto/tutorial-using-windows-defender-update-definitions-and-scan-for-viruses/

Alternatively - - -

You may prefer to install a third party antimalware program (which should disable Windows Defender) and you’ll no longer be concerned with the various issues that intermittently affect Windows Defender on Win 10.

There are a number of viable free and paid options available – take your pick…

Choosing an Anti-Virus Program

Is Windows Defender The Best For Windows 10?  Good article but ignore the ads.

http://www.dslreports.com/forum/r30380692-AV-Poll-2015

http://windows.microsoft.com/en-US/windows/antivirus-partners#AVtabs=win10

Regards…

http://blog.emsisoft.com/2015/01/27/top-10-ways-pups-sneak-onto-your-computer-and-how-to-avoid-them/

Answer 2

I have only had this laptop for a week and have never installed any third-party AV software. Today I got the same error from Windows Defender and it will not reactivate. It must have to do with an update. 

You may be right....if so then the issue should clear on its own - hopefully in a few hours.

My new Dell laptop included a trial version of McAfee that I uninstalled and I then used the McAfee Consumer Products Removal Tool.  Windows Defender has worked without issue for me since I did so.

Hope you get your issue resolved.

Answer 3

I have only had this laptop for a week and have never installed any third-party AV software. Today I got the same error from Windows Defender and it will not reactivate. It must have to do with an update.