Внимание! Windows 11 — относительно свежая версия операционной системы от Microsoft, поэтому с течением времени некоторые элементы графического оформления и наименования определенных пунктов меню могут изменяться. Но приведенные в статье методы все равно будут оставаться актуальными.
Способ 1: Обновление системы
Ошибка при открытии Windows Defender наблюдается только в ранних сборках операционной системы, поэтому перед применением серьезных мер следует проверить наличие обновлений и при необходимости выполнить их установку. Делается это стандартными средствами через меню параметров:
- Раскройте меню «Пуск», кликнув по соответствующей иконке на панели задач или нажав клавишу Win на клавиатуре. После появления соответствующего элемента интерфейса перейдите в раздел «Все приложения».
- Пролистайте список установленных на компьютере программ до буквы «П» и запустите «Параметры».
- В появившемся окне на боковой панели слева перейдите в раздел «Центр обновления Windows» и при наличии кнопки «Проверить наличие обновлений» нажмите по ней.
- Если новая версия операционной системы есть, то процесс загрузки и установки произойдет автоматически. Ход выполнения этой операции будет отображаться в этом же меню.
- При необходимости следует перезапустить компьютер. Об этом будет свидетельствовать появление соответствующей кнопки. Нажмите по ней.
Читайте также: Как обновить операционную систему Windows 10 / 8 / 7 / XP
На корректную работу «Защитника Windows» может влиять отсутствие дополнительных обновлений, их тоже потребуется проверить:
- В разделе «Центр обновления Windows» перейдите в меню «Дополнительные параметры».
- Включите опцию «Получать обновления для других продуктов Майкрософт», переведя переключатель в активное положение.
- Спуститесь ниже до блока «Дополнительные параметры» и зайдите в раздел «Необязательные обновления».
- Откройте выпадающие списки всех категорий (при их наличии) и установите отметки у каждого пакета. После этого запустите процесс обновления, кликнув по кнопке «Скачать и установить».
Останется дождаться завершения процедуры инсталляции всех новых апдейтов, после чего выполнить перезапуск компьютера.
Читайте также: Как включить или отключить Windows Defender
Способ 2: Сброс параметров «Защитника Windows»
Если после обновления и перезагрузки системы проблема со службой Windows Defender не устранилась, потребуется выполнить сброс параметров. Делается это посредством ввода специальной команды в окне консоли:
- Раскройте меню поиска, кликнув по соответствующей иконке на панели задач. Введите в поле запрос «Windows PowerShell», после чего нажмите по пункту «Запуск от имени администратора».
- В окно открывшейся консоли введите следующую команду и нажмите клавишу Enter для выполнения:
Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage - Дождитесь завершения перезапуска службы защиты, после чего попробуйте повторно открыть Windows Defender.
Читайте также: Как полностью удалить «Защитник Windows»
Обратите внимание! При выполнении введенной команды никакой текст в консоли не отображается. Процедура будет выполнена, когда появится новое предложение для ввода.
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When Windows Defender isn’t working, it’s most likely due to system file problems, or because you have or have had a third-party antivirus installed on your PC. Also, Windows Defender may not open if the Security Center is disabled.
No matter the specific issue, the solutions below should help you sort it out.
How do I fix Windows Defender not working?
1. Check your system files
1.1 Run a SFC scan
- Press the Windows key + S, type cmd, and click on Run as administrator to start Command Prompt as administrator.
- Type the following command and hit Enter, then wait for the scan to complete:
sfc /scannow
The System File Checker repairs corruption in system files. You can use it to verify whether Windows Defender is corrupted or not.
If you can’t run an SFC scan or if SFC can’t fix the problem, you might want to try using a DISM scan instead. To do that, just follow the next step.
1.2 Run a DISM scan
- Start Command Prompt as administrator, as shown in the previous step.
- When Command Prompt opens, enter the following command and press Enter to run it:
DISM /Online /Cleanup-Image /RestoreHealth
- DISM scan will now start. This scan can take up to 20 minutes, so don’t interrupt it.
2. Clean boot your computer
- Press Windows Key + R and enter msconfig. Press Enter or click OK.
- The System Configuration window will now appear. Go to the Services tab and check Hide all Microsoft services. Now click the Disable all button.
- Navigate to the Startup tab and click Open Task Manager.
- Now you’ll see a list of startup applications. Right-click the first entry on the list and choose Disable. Repeat this step for all startup applications.
- Once you disable all startup applications, go back to System Configuration window and click Apply and OK. Now choose to restart your PC.
Sometimes third-party applications can interfere with Windows and cause this problem to appear. However, you can find the problematic application by performing a Clean boot.
3. Remove third-party antivirus tools
If you have another antivirus installed on your PC, it can interfere with Windows Defender. To make it work, uninstall said antivirus. Then make sure it’s completely gone by following the steps below:
3.1. Delete leftover files from Program Files
- Open File Explorer (press Windows + E or search for it in the Start menu).
- Go to This PC and then open the C: drive.
- Open both Program Files and Program Files (x86) folders.
- Look for folders related to your antivirus software (e.g., Norton, Avast, McAfee) and delete them by right-clicking the folder and selecting Delete.
- In File Explorer, click on the View tab and check the box for Hidden items to show hidden folders.
- Delete any files and folders related to your antivirus.
3.2. Use an uninstaller software
- Download and install a reliable uninstaller software such as IObit Uninstaller.
- Go to the Software Health Section.
- Locate your Uninstallation Leftovers and Select Scan Now.
- Select and delete any remaining files or registry entries found by the scan.
Uninstall the remnants of your previous antivirus, restart your computer and Windows Defender should be automatically enabled.
⇒ Get IObit Uninstaller
4. Restart the Security Center Service
-
1. Press Windows key + R to launch the Run app.
-
2. Type services.msc in the Run dialog box and hit Enter or click OK.
-
3. In Services, search for Security Center.
-
4. Right-click on it and select Restart.
-
5. Once you restart the required services, check if the problem with Windows Defender is resolved.
In order for Windows Defender to work properly, you need to have certain services enabled. If those services aren’t running properly, Windows Defender won’t be able to turn on at all.
However, you can always start the necessary services by performing the steps above.
5. Change your group policy
NOTE
If you’ve got a Windows Home version installed on your PC, you will not have access to the Group Policy Editor. However, you can follow our expert guide to install it.
- Press Windows Key + R and enter gpedit.msc. Now press Enter or click OK.
- When Group Policy Editor opens, in the left pane navigate to the following path:
Computer Configuration/ Administrative Template/ Windows Components/ Microsoft Defender Antivirus - In the right pane, double click Turn off Microsoft Defender Antivirus.
- Select Not Configured and click on Apply and OK to save the changes.
Sometimes Windows Defender won’t turn on because it’s disabled by your group policy. After making these changes, it should work.
6. Modify your registry
6.1 Use the Registry Editor
- Press Windows Key + R and enter regedit. Press Enter or click OK.
- When Registry Editor opens, navigate to this key in the left panel:
HKEY_LOCAL_MACHINE/SOFTWARE/Policies/Microsoft/Windows Defender - In the right pane, look for DisableAntiSpyware DWORD and double click it.
- If the DWORD isn’t available, right-click the right pane and choose New and select DWORD (32-bit) Value from the menu.
- Set Value data to 0 and click OK to save the changes.
6.2 Use Command Prompt
- Start Command Prompt as an administrator.
- Now enter the following command and press Enter to run it:
REG ADD "HKLMSOFTWAREPoliciesMicrosoftWindows Defender" /v DisableAntiSpyware /t REG_DWORD /d 0 /f
If you’re an advanced user and you prefer using the command line, you can do this from Command Prompt or PowerShell by performing the previous steps.
Some users are also suggesting deleting the DisableAntiSpyware DWORD key, so you might want to try that as well.
7. Restart Windows Defender
- Type Windows Security in the Search bar, and click on App settings on the right.
- Now, scroll down, locate the Reset button, and click on it.
- Again, click Reset in the confirmation prompt that appears.
8. Install a better antivirus
Windows Defender is a decent security solution for your PC, but it can’t match the services and features of a third-party antivirus.
If you’re using the Internet for shopping, banking, work, and communication, you must protect your sensitive data with a top antivirus like the one recommended below.
This tool supports all major platforms, including Windows and Android, and provides advanced banking and privacy solutions.
Over 110 million users trust ESET’s multilayered protection solution in the world so make sure you try it. You can benefit from a 30-day trial period right now.
ESET HOME Security Essential
Make sure to fully protect your PC with a top antivirus solution like ESET HOME Security Essential.
Wrapping up
With that, we conclude our guide. We hope that our solutions helped you fix this Windows Defender not opening problem for good.
We also have a guide that explains what to do if you cannot open Windows Defender Scans folder, so don’t miss it.
If you’re an advanced user, you can use CMD virus scan command to get rid of the malware.
For any other suggestions on how to deal with this problem, write us a comment below.
Madalina Dinita
Networking & Security Specialist
Madalina has been a Windows fan ever since she got her hands on her first Windows XP computer.
She is interested in all things technology, especially emerging technologies — AI and DNA computing in particular.
Prior to joining the WindowsReport team, she worked in the corporate world for a number of years.
Key Takeaways
- Windows Defender is essential to keep your system safe while using the internet or downloading files.
- However, due to a few issues, the Windows Defender may not turn on at all.
- Let us see the Windows Defender not turning on error in Windows 11/10/8/7, how to fix it with simple methods, and how to use a free backup tool — EaseUS Todo Backup to protect your data on your computer from viruses or malware.
How to Fix Windows Defender Won’t Open/Working
Let us dive right into solutions to fix the Windows Defender if it is not working properly. Try these 7 methods one after the other to see if the problem is solved.
- Fix 1. Turn On Real-Time Protection
- Fix 2. Temporarily Disable Third-party Antivirus Program
- Fix 3. Restart the Security Center Service
- Fix 4. Run SFC Scan
- Fix 5. Enable Windows Defender via Group Policy
- Fix 6. Turn on Windows Defender via Registry Editor
- Fix 7. Update Windows
Fix 1. Turn On Real-Time Protection
Windows Defender comes with a real-time protection feature, and if it is turned off, you cannot open or run the app. Also, a major chunk of features are associated with Real-Time protection. So we have to check and turn it on back.
Step 1. Press Windows + S, search for Settings, and open it. Now, navigate to Update & Security from the left panel.
Step 2. Open the Windows Security section and click on Virus & Threat Protection.
Step 3. Now, head to the Virus & Threat Protection section and click the Manage Settings link from the options.
Step 4. In the new window, turn on the toggle for Real-Time protection. Restart the computer to see the changes.
Fix 2. Temporarily Disable Third-party Antivirus Program
A major reason why the Defender tends to act up is the conflicts due to third-party antivirus. So, to solve the problem, we can try to temporarily disable the third-party antivirus and check if the app works. Steps to temporarily disable antivirus are given below:
Note: Not having an active Antivirus program is prone to external risks. So, if you wish to disable antivirus, do it only if you are aware of the potential risks.
Step 1. Right-click on the empty space on your taskbar and click on Task Manager.
Step 2. Expand the Task Manager window to see the contents in more detail.
Step 3. Click on the Start-up on the header menu at the top. Now, find the antivirus program installed on your device from the list.
Step 4. Click on the program to select it, and click the Disable button at the bottom.
Step 5. Now, you have disabled the app from launching at the start. Restart the PC to see if the changes work.
If you remember your antivirus program account’s password, uninstall the program to see if it works.
Fix 3. Restart the Security Center Service
Windows operating system uses various services to run the functions and tasks smoothly. Similarly, the Defender uses the security service to roll out protection measures on your PC. We can try restarting the service to see if it resolves the problem.
Step 1. Press the Windows + R keys to open the Run dialog box. Type the services.msc command and press Enter.
Step 2. The services window will open, and you can find the Security Center service from the list.
Step 3. Right-click on the service and select Refresh from the menu.
Step 4. This action will restart the security service. Now, try and check if the Windows Defender is turning on or not.
Share this article on your social media to help more people out.
Fix 4. Run SFC Scan
SFC, abbreviated System File Checker, scans and restores the Windows system files for errors and corruptions. If any Windows files are responsible for the Microsoft Defender not working, an SFC scan may restore the original files.
Step 1. Open Command Prompt (CMD) with the administrative privileges.
Step 2. Type the SFC scan command and press the Enter key.
sfc /scannow
Now, the SFC will start the system scan. This will take some time, and you have to wait until the verification reaches 100%. After that, close the CMD and check if the Windows Defender unexpected error is resolved.
If the SFC scan fails to work with some error message, you can run the below DISM command to fix the issue.
DISM /Online /Cleanup-Image /RestoreHealth
Fix 5. Enable Windows Defender via Group Policy
Local Group Policy Editor lets you change the files in the OS. By accident or by another user, your system may have entirely turned off the Windows Defender in Group Policy. In some cases, even malware is capable of doing this. So, let’s check the Group Policy and turn the Windows Defender back on.
Step 1. Press Windows + S, and type Group Policy. Click on Edit Group Policy from the results.
Step 2. Now, navigate to the following location to find the Microsoft Defender Antivirus in Local Group Policy Editor: Computer Configuration → Administrative Templates → Windows Components → Microsoft Defender Antivirus.
Step 3. Double-click on Turn off Microsoft Defender Antivirus to open a new window.
Step 4. Toggle the button beside Not Configured, and click on the Apply button. Restart the computer to see if the Defender Antivirus is back working.
Fix 6. Turn on Windows Defender via Registry Editor
You need to be a Windows 10 business user to make changes through the Group Policy Editor. But you can enable the Windows Defender using Windows Registry. Let us see how to change the Registry Editor to enable Windows Defender.
Step 1. Press the Windows + R keys on your keyboard to open the Run dialog box.
Step 2. Type regedit and hit Enter to open the Registry Editor window.
Step 3. Paste the path in the Navigation pane to open the Windows Defender.
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
Step 4. Find the registry entry named DisableAntiSpyware from the list and click on it.
Step 5. If you do not see an entry with the name, right-click on any empty space and click New > DWORD (32-bit) Value. Name the entry as DisableAntiSpyware, and double-click to open it.
Step 6. Set the Value data to 0, and click OK. Exit the Registry Editor window. Restart your computer to see if you are able to open Windows Defender.
Fix 7. Update Windows
Generally, you can check for updates if the issue is with Windows OS. If you find any new updates, download them to see if the error resolves.
Note: It is important to back up your system to keep your data safe. So, before updating, make a copy of your data in emergencies.
Step 1. On Windows 10, navigate to Settings > Update & security. On Windows 11, open the Settings > Windows Update.
Step 2. Click on Check for updates. The system displays the available updates for the OS.
Step 3. Install the updates and restart the system to see if the Defender turns back on.
If you encounter a black screen error after updating your Windows, you can refer to the following article for help.
How to Fix Windows 10 Black Screen After Update
Windows 10 black screen after update error is one of the most common errors users face after updating their system. If you are also one of those, you should read this blog as we have discussed 9 methods to fix this error here. Read more >>
How to Protect Your PC’s Data from Virus Attack
As we have discussed, if your Windows Defender is not turning on, your system is at risk of external threats. If the defender is not working, and you do not have an active antivirus plan, you may lose your data from virus or malware attacks. In such instances, the best way to protect your PC’s data is to back up your system and restore it whenever needed. EaseUS Todo Backup, a free backup program, can help you.
It is a reliable backup tool with advanced backup solutions. Along with backing up your entire system, you can make bootable USB drives in case of virus or trojan attacks. You can use it to perform full, incremental and differential backups and save them in various locations. The following are some key features of this backup tool.
- Transfer operating system from one computer to another
- One-click backup & restore options with a simple interface
- Create a system image of Windows on an external hard drive
- Clone a hard drive and image a hard disk with several clicks
- Provide 250G free Cloud storage to back up files to the Cloud
Apart from protecting from viruses and malware attacks, EaseUS Todo Backup can help keep your data safe in case of failing drives, physical damage, or any sudden emergency. Back up your data or computer now with EaseUS backup software to safeguard data from malware or virus threats.
Step 1. Launch EaseUS Todo Backup on your computer, and click Create Backup on the home screen and then hit the big question mark to select backup contents.
Step 2. To back up your Windows operating system, click «OS» to begin the backup task.
Step 3. Your Windows operating system information and all system related files and partitions will be automatically selected so you don’t need to do any manual selection at this step. Next, you’ll need to choose a location to save the system image backup by clicking the illustrated area.
Step 4. The backup location can be another local drive on your computer, an external hard drive, network, cloud or NAS. Generally, we recommend you use an external physical drive or cloud to preserve the system backup files.
Step 5. Customiztion settings like enabling an automatic backup schedule in daily, weekly, monthly, or upon an event, and making a differential and incremental backup are available in the Options button if you’re interested. Click «Backup Now«, and the Windows system backup process will begin. The completed backup task will display on the left side in a card style.
Why Is Windows Defender Not Tuning On
The Windows Defender is not turning on or launching. Like how many default apps become corrupt over time, the Defender may face the same issue due to Windows updates or existing malware infections.
Another prevalent reason is downloading a third-party antivirus causes conflicts between each other and will stop the Microsoft Defender from turning on. If you are downloading any third-party antivirus like TotalAV, Norton, or McAfee, it is suggested to disable Windows Defender to run the security checks smoothly.
Here’s a list of most common reasons why Windows Defender is not launching on your PC:
- Conflicts between Defender and third-party antivirus.
- If the time and date of your computer are out of sync.
- Due to a system configuration error present in the device.
- If you have disabled Windows Defender using Group Policy Editor.
- Registry Edit changes are preventing Windows Defender from launching.
- The Windows Defender service is disabled.
The Bottom Line
If you meet the Windows Defender not turning on error, you must fix it ASAP to avoid getting into trouble. Learn how to fix the Windows Defender not working or opening in the post and secure your data.
The best method is to back up your system to protect your PC from external threats or system crashes. Use EaseUS Todo Backup, a professional and free backup tool, to back up your data automatically. Download and try it!
Here are some of the most frequent FAQs asked on Windows Defender not turning on. I hope you find these queries helpful.
1. How do I reinstall Microsoft Defender?
To reinstall Windows Defender, follow the steps below:
- Open the Windows Terminal with administrator privileges.
- Execute the command below to reinstall Microsoft Defender:
Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage
2. Can Windows Defender be permanently disabled?
Yes, though it is hard, you can still permanently disable Windows Defender.
- Edit the Group Policy Editor.
- Change the Registry Editor settings.
- Run the below command with CMD.
reg add «HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Microsoft Defender» /v DisableAntiSpyware /t REG_DWORD /d 1 /f
3. Why is Windows Defender not removing a virus?
There are a few reasons that stop Windows Defender from removing a virus.
- If your C drive does not have enough space for the defender to quarantine the malware.
- Temporary files, cookies, and app log files restrict the app.
If a simple restart doesn’t help, you can reset Windows Security in seconds
Updated on September 10, 2022
Windows Defender not opening or working correctly could mean you can’t edit any of its settings in Windows Security, or malware can run amok on your system because you don’t have the proper security in place. Below are several reasons why Windows Defender doesn’t open and how to get it working again.
Why Windows Defender Won’t Open in Windows 11
Here are some examples of situations where Microsoft’s anti-malware app won’t open or work properly:
- There’s a temporary memory-related issue where the app won’t scan for malware.
- Windows Security opens normally, but then promptly closes a few seconds later.
- Another software program is «fighting» with Windows Defender, and it’s throwing error messages.
- You see an error that says, «You’ll need a new app to open this windowsdefender link.»
- You recently installed or uninstalled another virus protection program, and now Windows Defender won’t open.
Windows Defender is called Microsoft Defender in Windows 11, and it’s managed through Windows Security. These names are used interchangeably in this article, but we’re referring to the same tool.
How to Fix Windows 11 Defender Not Working
There are several things you can try, but follow this list in the order it’s presented to address the easier solutions first:
-
Restart your computer. This is a very common first step when troubleshooting basically anything in Windows, and it might just be all you have to do to get Windows Defender working again.
-
Turn off Windows Defender, and then turn it back on. Or, if it was off to begin with, that article shows you how to turn it on.
Microsoft Defender won’t catch active malware unless you have Real-time protection turned on.
This step is useful if, in your situation, «Windows Defender not working» simply means that it isn’t checking for malware. If you can’t open Windows Security in Settings, then move on to the next step.
-
Repair or reset Windows Security. A repair will have Windows attempt to fix whatever is going on, and a reset will erase all the app’s settings and start over as if Windows Defender was just installed.
Follow that link for two methods—one uses Settings, like in the image below, and the other uses a PowerShell command that’s helpful if you can’t open Windows Security at all.
-
Update Windows. This is how Microsoft delivers bug fixes, so an update you’ve yet to install could address the Windows Security issue.
If that doesn’t work, you can try an offline Microsoft Defender update. Choose the latest version from that list, likely called Update for Microsoft Defender Antivirus antimalware platform.
To avoid getting an update you don’t need, you can check your current version from Settings > Privacy & security > Windows Security > Open Windows Security > Settings > About.
-
This step is for when your problem is so specific the only issue you’re running into is you can’t seem to clear out the Protection history screen in Windows Security, or you’re told a threat was found, but there’s nothing to clear out.
To address this, open the following folder. One easy way to do this is to paste this path into the Run dialog box (WIN+R):
C:\ProgramData\Microsoft\Windows Defender\Scans\History\Service\Select everything in the Service folder (Ctrl+A), and then press Delete to clear it out.
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Temporarily disable any other antivirus programs you have installed. How this works is different for every app, but doing so should give you some time to see if Windows Defender’s troubles were due to a compatibility issue with the other anti-malware tool.
If you find the other program is to blame, or you suspect it might be but disabling it didn’t help, use a program uninstaller tool to completely delete the software.
If you still can’t start Windows Defender, there are a couple of registry keys you can delete to re-enable it. This might happen after uninstalling another antivirus program.
Open this key, and delete these two registry values from there:
DisableSpyware and DisableAntivirus.HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Your computer might not have these registry values, since they most likely exist only if security settings have been implemented via group policy (e.g., an IT department). If so, just move on to the next step.
-
Run the SFC /scannow command to repair system files. This will invoke the System File Checker tool to see if there are any problems with protected Windows files, and then replace them if so.
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Use Reset This PC to reinstall Windows 11. Although this will reinstall Windows and reset all your programs back to their factory default state, that’s exactly what you want in this situation.
This is a sure fix for whatever problem is affecting Windows Defender, just make sure you wait until you’ve tried all the above before completing this drastic step.
Choose carefully to keep or wipe your data when resetting your PC.
FAQ
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Go to Settings > Privacy & Security > Windows Security > Virus & threat protection > Manage Settings. Under Exclusions, select Add or remove exclusions.
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No, not technically. Windows Firewall is a feature of the Windows Defender software. There is no separate Windows Firewall program.
-
To turn off SmartScreen in Microsoft Edge, go to the three-dot menu > Settings > Privacy, search, and services. Under Services, turn off Microsoft Defender SmartScreen.
Thanks for letting us know!
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When I browse through forums I often find this question asked many times – I am unable to turn on Windows Defender manually or Windows Defender won’t or will not turn on and start in Windows 11 or Windows 10. If you face this issue, then this post may help you.
If you are unable to start Windows Defender, then one of these suggestions is sure to help you:
- Check if you have another security software installed
- Check the date or time on your PC
- Run Windows Update
- Check Internet Zone settings
- Check Group Policy setting
- Check Registry setting
- Check the status of Service
- Scan PC with portable antivirus software
- Check the value of AllowUserUIAccess.
Let us see the suggestions in detail.
1] Check if you have another security software installed
One of the most common behaviors 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 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, it 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 may be unaware if security software is indeed installed or not because when you buy a new laptop, it mostly 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 scanners when most of them don’t notice. So it’s best to search your PC if you’re not sure if security software is installed or not. Once it’ removed you may need to turn it manually back on.
Type “Windows Defender” in the search box and then press Enter. Click Settings and make sure there is a checkmark on Turn on real-time protection recommend.
Open Windows Security > Virus protection and toggle the Real-Time Protection switch to On position.
2] Check the date or time on your PC
The other issue that could cause Windows Defender not to work properly is the incorrect date or time on your Windows machine. Make sure you have set your Windows clock & date set properly and then try to turn your Windows Defender back on and see if it works fine. It’s strange, but 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.
3] Run Windows Update
Another important thing that could cause issues is if your Windows is not up to date in terms of Windows Update. This could cause issues in Windows Defender or any other Windows core application. Any security software always needs the latest signature updates and other Windows core updates to keep your PC secure. So I would highly recommend running 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.
Read: Cloud-delivered protection is off, Your device may be vulnerable
4] Check Internet Zone settings
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 be an 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 must make small changes to your Proxy server.
Press Windows + X and select Command Prompt (Admin)
Type in the following and hit Enter:
NETSH WINHTTP SET PROXY 1.1.1.1:8080
or
NETSH WINHTTP SET PROXY MYPROXY.NET:8080
Now reboot the system and see if it works.
5] Check Group Policy setting
Open Group Policy Editor and navigate to the following setting:
Computer Configuration > Administrative Template > Windows Components > Windows Defender Antivirus.
SIn the right pane, double-click on Turn off Windows Defender Antivirus.
Next, select Not Configured, click the Apply and OK button.
6] Check Registry setting
Open Registry Editor and navigate to the following setting:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
Locate DisableAntiSpyware key. If this key is not present, create a new and DWORD (32-bit) Value.
Set its Value data to 0 and exit.
7] Check the status of Service
Run services.msc to open Services Manager. Ensure that the Windows Defender service is started and set to Automatic.
8] Scan PC with portable antivirus software
Finally, it could be a malware itself that’s causing Windows Defender not to work properly. You could download and use Windows Defender Offline Tool or any other standalone antivirus software and run a complete scan.
9] Check value of AllowUserUIAccess
If under Windows Security settings, the option for “Virus & threat protection” has disappeared, then Andrew suggests the following:
Run Registry Editor as Administrator and go to:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Policy Manager
Set value of AllowUserUIAccess to 1.
These are some common reasons why Windows Defender does not start.
PS: Windows Defender is turned off or not working offers some additional troubleshooting suggestions, which may also interest you.
You may also want to check out these posts which help troubleshoot Windows Defender problems:
- Error 0x800106a, Windows Defender will not turn on
- Windows Defender Error Code 0x800106ba: Application failed to initialize
- Windows Defender Error: MSASCui.exe – Unable To Locate Component
- Error 0x80070422 The Service Couldn’t Be Started in Windows Defender
- Error 0x80508020, 0x800705b4 for Windows Defender.