Can't download Defender

Open the official Microsoft Defender Store listing, select Install, and then sign in to Defender with the personal Microsoft account associated with Microsoft 365.

Install the correct Defender app

1. First search the Start menu for Microsoft Defender. It may already be installed automatically with Microsoft 365.
2. If it is not installed, open https://aka.ms/WindowsDefender and select Install.
3. Launch Microsoft Defender from Start and sign in with your personal Microsoft account. The app is not activated until you sign in. ^1^

The downloadable Microsoft Defender app is associated with Microsoft 365 Personal or Family. It is different from Windows Security and Microsoft Defender Antivirus, which are built into Windows 10 and 11 and do not need to be downloaded. ^2^

If the Store still says “Unable to download”

Perform these steps in order:

1. Reset the Store cache
   • Press Windows key + R.
   • Enter wsreset.exe, then select OK.
   • A blank window should appear briefly; after about ten seconds, it should close and Microsoft Store should reopen.
   • Return to the Defender listing and try Install again. ^3^
2. Update Windows and Microsoft Store
   • Windows 11: Start > Settings > Windows Update > Check for updates.
   • Restart if updates are installed.
   • Open Microsoft Store > Library > Get updates and allow any Store update to finish.
3. Repair Microsoft Store
   • Windows 11: Start > Settings > Apps > Installed apps.
   • Find Microsoft Store, select More (…) > Advanced options > Repair.
   • Try the Defender installation again.
4. Reset Microsoft Store if Repair does not work
   • Return to Microsoft Store > Advanced options and select Reset.
   • Reopen the Store, sign in with your Microsoft account, and retry the installation. Resetting clears the Store app’s local data, so use it only after Repair fails. ^4^

For Windows 10, the corresponding path is Start > Settings > Apps > Apps & features > Microsoft Store > Advanced options, followed by Repair and, if necessary, Reset. ^4^

Check eligibility only if Defender remains unavailable

• Confirm the Store is signed in with the intended personal Microsoft account, not only a work or school account.
• Test whether another free Store app downloads. If that also fails, the problem is with Microsoft Store rather than the Defender listing.
• Defender for Windows is currently unavailable in Belarus, Guernsey, Pitcairn Islands, Réunion, Russia, and Saudi Arabia. If your Store region is one of these, Store repair will not make the app available. ^5^
• If the goal is only antivirus protection for the PC, open Start > Windows Security instead; that protection is already built into Windows. ^2^

References

1. Installing Microsoft Defender | Microsoft Support
2. Getting started with Microsoft Defender | Microsoft Support
3. I can't find or install an app from Microsoft Store | Microsoft Support
4. Repair apps and programs in Windows
5. Microsoft Defender is not currently available in these regions | Microsoft Support