Windows Defender Error Code: 0x80073afc

Hi Robynn,

Thank you for posting your question in Microsoft Community.

You seem to have an issue with running Windows Defender on your computer. We will assist you in fixing the issue. Please answer the following questions to help me understand the issue better:

1. Did you use any other 3^rd^ party antivirus application on your computer?
2. Are you administrator of the computer?
3. Did you make any changes to the computer prior to this issue?

Some 3rd party antivirus programs may turn off Windows Defender when they are installed to be used instead, and will not allow Windows Defender to be turned back on until the 3rd party antivirus has been uninstalled or disabled.

Refer to these steps to turn on Windows Defender:

1. Press Windows and X keys together.
2. Open the Control Panel (icons view), and click/tap on the Windows Defender icon.
3. In Windows Defender, click/tap on the Settings tab, Administrators in left pane, uncheck the Turn on Windows Defender box, and on Save Changes.

Reference links for more information:

http://answers.microsoft.com/en-us/protect/forum/mse-protect\_start/an-error-has-occurred-in-the-program-during/6b838264-b590-4309-85f9-def16c597c31

http://answers.microsoft.com/en-us/protect/forum/mse-protect\_updating/microsoft-security-client-error-0x80073b01/1118f1c2-34e3-48f4-af57-3e066bcfa227

Hope this helps you. Please do let us know if you need further help.

Try methods given here serially and reply with their results:

Problems starting Windows Defender in Windows 8/8.1

Prashant Kumar