Troubleshoot problems with updating virus and spyware definitions for Microsoft Security Essentials.

Describes three methods that you can use to resolve an issue where Microsoft Security Essentials appears to be running correctly, but then reports that the computer is unprotected.

Get security info and tips about threat prevention, detection, and troubleshooting. Including tech support scams, phishing, and malware.

Select Device details Select Manage in Windows Security Select Quick scan Tips: If you want a deeper scan, instead of selecting Quick scan in step 3, select Scan options and choose the type of scan you want. For the most complete scan, run Microsoft Defender Offline. For more about that see Help protect my PC with Microsoft Defender Offline.

Describes how to resolve an issue where another security program has been installed on the computer and iw causing a conflict with Microsoft Security Essentials.

Windows Security app update This security update provides the latest changes for the Windows Security app. The update is composed of the Windows Security app and its underlying service. This update applies to only Windows 11 devices (build 22000 or later)

Microsoft Security Essentials is free and can help protect your home or your small business system from viruses, spyware, and other malware. For more information, visit the following Microsoft webpage:

Describes how to update Microsoft Security Essentials in a network that uses a proxy server.

It includes features such as Microsoft Defender Antivirus, Windows Firewall, and Smart App Control, which work together to provide real-time protection against viruses, malware, and other security threats.

Find out how Windows Security can help keep your PC safe from malicious software and viruses.