Unable to turn on Windows Defender in Windows 7 / 8 / 10

When I browse through forums I often find this question asked many times – I am unable to turn on Windows Defender in Windows 7 or Windows 8, or Windows Defender wont or will not turn on and start. In this post I’ll list some common issues that can affect Windows Defender.

Unable to turn on Windows Defender

Windows Defender

Scenario 1:

On of the most common behavior of Windows Defender is that if it detects a third-party antivirus software, then Windows Defender will shut itself off. Windows is designed to detect the presence of security software installed, and we often we get to see the notification in the Action Center. One of the common issues we have seen in the past, is when there are multiple security software installed. It often creates a conflict between them and in the end, in creates more trouble than doing any good. Frequent freezing, crashing to applications are some of the common issues which occur when you install more than one antivirus software.

So to avoid this situation Windows Defender will turn itself off when it detects another security program. Likewise if this security application has a Firewall then Windows Firewall will also stop working. So in case you want Windows Defender to work, then you will have to uninstall your third-party security software and reboot the system.

Often users maybe unaware if a security software is indeed installed or not because when you buy a new Laptop mostly it comes with a trial version of security software like Norton, McAfee etc. Then when you install applications like Flash or java it might prompt you to uninstall free security scanner when most of them won’t notice. So it’s best to search your PC if you’re not sure if a security software is installed or not. Once it’ removed you may need to manually turn it back on.

  • Press the Windows + Q key on the keyboard to bring up the charms search.
  • Type “Windows Defender” in the search box and then press enter.
  • Click Settings and make sure there is a check mark on Turn on real time protection recommend.

Scenario 2:

Then other issues than could cause Windows Defender to not work properly is incorrect date or time on your Windows 8 machine. Make sure you have set your Window clock & date set properly and then try to turn you Windows Defender back on and see if it works fine. It’s strangebut most of the Windows operating system functions work, based on the system date and time. So an incorrect date or time could trigger abnormal behavior in your Windows OS.

Scenario 3:

Another important thing that could cause issues is, if you Windows is not up to date, in terms of Windows Update. This could cause issues in Windows Defender or any other Windows core application. When it comes to any security software, it always needs the latest signature updates and other Windows core updates to keep your PC secure. So I would highly recommend to run a complete Windows Update, then go into Windows Defender and run an update from there as well. Then see if your Windows Defender is working fine.

Other Common Issues:

The above discussed scenarios are the most common ones. Apart from these, there could be some minor issues that could affect the working of Windows Defender. It could incorrect Zone setting in Internet Explorer, which you can fix by resetting Internet Explorer to factory settings. Again, if you are using a Proxy server, Windows Defender will not be able to update.

In such cases, you need to make some small changes to your Proxy server.

  • Press Windows + X and select Command Prompt (Admin)
  • Now reboot the System and see if it works.

Finally, it could a malware itself that’s causing Windows Defender to not to work properly. You could download and use Windows Defender Offline Tool or any other standalone antivirus software and run a complete scan.

These are some common reasons why Windows Defender does not start.

Windows Defender is turned off or not working offers some additional troubleshooting suggestions, which may also interest you.

You may want to also check out these posts which help troubleshoot Windows Defender problems:

  1. Error 0x800106a, Windows Defender will not turn on
  2. Windows Defender Error Code 0x800106ba : Application failed to initialize
  3. Windows Defender Error : MSASCui.exe – Unable To Locate Component.
Posted by on , in Category Security with Tags
Shyam aka “Captain Jack” is a Microsoft MVP alumnus and a Windows Enthusiast with an interest in Advanced Windows troubleshooting. Suggestions made and opinions expressed by him here are his personal one's and not of his current employers. He blogs at captaindbg.com.
  • mike

    wow…what a tasking and so many articles to read to accomplish the turn on of windows defender….finally accomplished it…..first step was to uninstall MacAfee, restart system, second step was to right click on the MacAfee app and unpin to startup, restart system, proceed to apps and click on windows defender app and rest is history so to speak. follow instruction , pin to startup, visit security center, click turn on firewall and windows defender comes alive, run a scan and the win 8pc is fully protected….

  • mychele bustamante

    Finally I was able to turn on windows 8 defender. Make absolutely sure all other anti virus protection is removed from your computer. (I had to uninstall Norton more than once) Go to Control Panel, security system, action center. DONE!!!! Yeah, whoo finally it worked!

  • Haskel Pippin

    My question is: How does Windows Defender compare to other programs that are currently on my computer, in ridding it against viruses, malware, spyware and other outside forces attempting to invade and do harm to it? In other words, can I rely solely on Windows Defender, to do what other programs have, up until now, done.

  • http://thewhizzer.blogspot.com/ Buck

    Download Ultimate windows there are many tweaks on there, it does not go on your programmes either, just a suggestion

  • http://www.thewindowsclub.com Anand Khanse

    Yes, you can. Windows Defender in Windows 8 should suffice.

  • http://thewhizzer.blogspot.com/ Buck

    I meant to say Ultimate windows tweaker not Ultimate windows. it can also be done there,sorry about that

  • http://www.thewindowsclub.com Anand Khanse

    OK :)

  • http://thewhizzer.blogspot.com/ Buck

    No worries Anand

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  • Wade McKay

    unable to open win7 defender.
    read and followed the below posts and still get “click here to turn on” and it times out. nothing.

  • http://www.thewindowsclub.com Anand Khanse
  • Wade McKay

    No, nothing accomplished yet but thank you anyway.
    Is there a need for defender since I’m running security essentials?
    Take care, Wade

  • http://www.thewindowsclub.com Anand Khanse

    On Windows 7, Microsoft Security Essentials offers anti-virus and anti-malware protection, whereas Windows Defender offers anti-spyware protection. Do not remember for sure, but maybe MSE has disabled Defender. You should be safe with just MSE on Windows 7.

  • Ateeq Anjum

    i have much problem because a virus send anyone to know passwords and data, which is close or off mine windows defender and look this error show: http://prntscr.com/5fnmpz
    plz help me what i do?

  • http://www.thewindowsclub.com Anand Khanse

    Open Run box, type services.msc and hit Enter to open the Services Manager. Double-click on and set the Windows Defender Service on Automatic. Also ensure that Windows Defender Network Inspection Service is set on Manual. Start both the Services manually using the Start button and see if it helps. Also download and scan your PC with portable antivirus software: http://www.thewindowsclub.com/standalone-on-demand-antivirus-scanners

  • ctblizzard

    I appreciate the article but this “improvement” to Windows actually sucks. First off, most new PCs come loaded with a trial of anti-virus software. Which often expires ,but even if you never used it Windows defender does not kick in give a scan or tell you to delete it. Even if it did deleting these things is a problem. Second, on prior versions of windows I have always used multiple programs and that process works. On a Windows 7 laptop I had Malwarebytes, MS security essentials both of which missed somes stuff that I found with Avast. There have never been any problems running any of these programs. Lastly, usually when you need something the most is when you have a problem. You have an anti-virus installed and no matter what you do you cant get the damn defender to work. You cant force it to turn on, you cant even run as administrator. Poorly thought out product.

  • Justin G

    absolutely not true, Windows defender is easily shut down by malware, spyware and virus. the administrator rights are taken over and you can not gain access bact to turn on defender. Odin Virus. Windows defender defends against nothing. look for a better anti-adware,virus and spyware blocker and remover like Spybot!!!

  • TheLastWordManiac

    true. that just happened to me. it got shut down and i can not turn it back on. now using kaspersky

  • Russell Doherty

    I fixed this problem by using system restore which recovered an installation of IOBit Malware Fighter that I had previously uninstalled. I then uninstalled IOBit Malware Fighter again and this time Defender was reactivated and all is well.

  • amanda

    I am so frustrated right now :( I have tried everything!! I didn’t have any other virus protection stuff on my laptop, I have checked my programs for unknown programs, done a registry clean and I have even tried the command prompt thing but to no avail have I been able to fix the solution. My computer was working fine and then bam! this happened. I haven’t downloaded anything recently except the windows updates. can someone help?? on windows 8.1 Acer with a 64 bit system..

  • acornbuilder

    My Windows Defender will not open: “An error has occurred during initialization. If this problem continues, please contact your system administrator. Error code: 0x80073b01”
    Where do I start? Would really appreciate some not-too-technical advice.

  • diwanshu mahajan

    i am also suffering from same problem . tell me how i can protect my pc

  • diwanshu mahajan

    suffering from same issue tell me what to do

  • eddie

    great info !!..finally my windows defender are turn back on..just simply update my Windows Update..and then update the Windows Defender..and its all work as it used to be..thank you

  • Db Ben

    seems that when i installed xerox’s rampport security software provided by my bank, defender icon would pop up with a red x. eventually, i uninstalled that security software because it was slowing down the system. but afterwards, i could not figure out how to turn defender back on, in spite of all the info on the word wide web and my personal efforts. but the defender program would run ok when i manually ran it but would still leave the flag with the red x enabled and bugging to turn it on.

    eventually, i opened defender and proceeded to “turn off real time protection”, then closed. the flag with the red x then provided a message about turning on and to click it. so i did, it then opened defender and showed me that the real time protection was then set to enabled. the white flag then appeared without the red x.

    so bottom line- dont’ be fooled into thinking the “real time protection” being enable is evidence that defender is protecting in real time. instead, cycle that option to disable while the program is open. and then re-try to “turn on” defender via the flag icon.

  • Farooq Amjad

    An unwanted software has taken the control of my laptop.It is not shown in programs and features and has inactivated the Windows Defender…I am unable to remove it from action centre…. and to stop it from working….
    It is in Some what chinese or japanese language….
    Any body plz help to get rid of it and Activate the windows defender….
    Thanks In Advance

  • http://www.thewindowsclub.com Anand Khanse

    Boot in Safe Mode and run your antivirus software. Else use one of these portable security software and scan your PC, from a USB. Dr WEB Cure It is good – http://www.thewindowsclub.com/standalone-on-demand-antivirus-scanners

  • Mike

    I had forgotten I had MS Security Essentials running, which turns of Windows Defender.

  • omegaman

    Windows Defender is a piece of crap.

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