The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →If Microsoft Defender Antivirus appears turned off after Windows Update, first check which antivirus provider Windows Security shows as protecting your PC. A compatible non-Microsoft antivirus can automatically put Defender into disabled mode, so the timing alone does not prove that an update caused the change. If no other provider is active, check Defender’s real-time protection setting, then confirm that security intelligence is current.
Why is Microsoft Defender turned off after Windows Update?
The cause depends on the PC. Microsoft says compatible non-Microsoft antivirus software can automatically turn Microsoft Defender Antivirus off while that product is in use. Windows Update may simply have happened around the same time; Microsoft’s documentation does not establish a universal post-update defect.
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Start by checking the provider Windows recognizes, rather than trying to force Defender on alongside another antivirus product.
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →How do I check which antivirus provider is active?
- Open Windows Security.
- Select Virus & threat protection.
- Under Who’s protecting me?, select Manage providers.
If a compatible third-party antivirus is listed and is working, Defender being disabled can be expected. Keep that product if it is the protection you intend to use. Microsoft warns that running multiple antivirus products can cause performance or stability problems; do not install or activate a second product as a default fix. If you uninstall the other antimalware software, Microsoft says Defender should return to active mode automatically. Microsoft’s provider and scan guidance explains how Windows Security reports protection status.
#1 Best Overall
- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key C NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key C NFC via USB-C and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
How do I turn Microsoft Defender Antivirus back on?
If no other antivirus provider is responsible, inspect the built-in real-time protection setting:
- Open Windows Security and select Virus & threat protection.
- Select Manage settings.
- Turn on Real-time protection.
Microsoft notes that real-time protection can be switched off temporarily and may turn itself back on later. While it is off, files you open or download are not checked by real-time protection. For the setting’s behavior and Microsoft’s description of compatible antivirus software, see Virus and threat protection in the Windows Security app.
Rank #2
- POWERFUL SECURITY KEY: The Security Key NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key NFC via USB-A and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
What if protection is on but security intelligence is out of date?
An active antivirus provider and current security intelligence are different checks. Windows downloads security intelligence through Windows Update, and you can also check for updates manually. If Defender protection is on but its protection updates repeatedly fail, Microsoft recommends trying to install the latest protection updates manually. Follow Microsoft’s malware detection and removal troubleshooting guidance for that update problem.
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What if the setting is unavailable or keeps switching off?
Tamper protection helps prevent apps from changing security settings. Microsoft says an administrator can still change settings in Windows Security when tamper protection is on, while other apps cannot. If Real-time protection is greyed out, repeatedly turns off, or the PC is controlled by an employer or school, check whether the device is managed and contact its administrator or Microsoft support. Avoid disabling tamper protection, editing registry values, or forcing Defender services to start; those steps can conflict with device management and are not the recovery path established in Microsoft’s guidance.
Rank #3
- POWERFUL SECURITY KEY: The YubiKey 5 NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
If another antivirus has been removed but Defender remains inactive, or you cannot turn on real-time protection, note your Windows version, the provider shown under Manage providers, the exact warning or error code, whether the PC is work- or school-managed, and whether security intelligence updates succeed. Give those details to Microsoft support or your organization’s support team.
Does Windows 10 still receive security fixes?
Windows 10 support ended on October 14, 2025. That lifecycle date matters when diagnosing a PC that still runs Windows 10: do not assume it continues to receive ongoing free Windows 10 security fixes through Windows Update. Check your Windows version and review Microsoft’s current guidance on Windows Security and device protection.
Rank #4
- Security Key : Protect your online accounts against unauthorized access by using FIDO2 and U2F authentication with T120. It's the world's most protective security key that works with windows, Mac OS, Linux as well as Chrome, Firefox, Edge and many other major browsers.
- Certified with the new FIDO2 standard, T120 provides the benefit of fast login and strong protection against phishing, account takeover as well as many other online attactks.
- Works with : Bank of America, Github, Google, Microsoft, DUO, Twitter, Facebook, Dropbox, Apple, ebay, BINANCE, mor and more.
- Fits USB-C port : Insert the T120 security key into the USB-C port of each service and log in conveniently with one touch
- For the driver download and user guide, please visit TrustKey Solutions Home support page.
Is the Windows Security troubleshooter worth trying?
Microsoft lists an automatic Windows Security troubleshooter for Windows 10 that checks items including antivirus status and updates. Treat it as a legacy Windows 10 option if it remains available, not the first fix for every PC. Microsoft’s page also notes that Windows 10 support ended on October 14, 2025, and that the Microsoft Support Diagnostic Tool (MSDT) is deprecated. See Automatically fix Windows security issues.
Quick Recap
Best Value
- POWERFUL SECURITY KEY: The YubiKey 5C NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5C NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5C NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
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