What's the Best Antivirus and Is Windows Defender Good Enough?.Open Command Prompt or Powershell and type in the following two lines, pressing Enter after each:Ĭonsider using Malwarebytes for complete antivirus protection and to protect your devices, data, and privacy. If the update fails, you can update from the Command Prompt: Browse to the folder where you saved the file, and then double-click Mpas-fe.exe to install the latest definition file. If your computer runs any other Windows operating system, you must be logged on as an administrator to install the latest definition file. When you are prompted for an administrator password or confirmation, type the password or provide confirmation, and then wait while the definition files are installed. Right-click Mpas-fe.exe, click Run as administrator and then click Run. If your computer runs Windows Vista, click Start, click Documents, and then locate the folder where you saved the definition file. To install the saved definition update file: If you click Save, remember the name of the folder where you save the file. Installation instructions for Windows Defender Definition Updates:Īfter you click this link, click Run to install the definition file immediately or click Save to save it to your computer. Windows Defender Antivirus Definition Updates for timely updating of your Windows Defender if the automatic update happens to fail.