How do I manually update Windows Defender?

Open the Settings app. Go to Update & security -> Windows Update. On the right, click Check for updates. Windows 10 will download and install definitions for Defender (if available).

Why is my Windows Defender not updating?

Check if you have other security software installed, as these will turn off Windows Defender and disable its updates. … Check for updates in Windows Defender Update Interface and try Windows Update if it failed. To do this, click Start> Programs> Windows Defender>Check for Updates Now.