I have been having this problem with windows defender for a very long time. Whenever I click the update definitions on Windows Defender I get an error code and it is unable to update. My AVG antivirus and Comodo firewall have no problems updating. Even my windows update works properly. I tried disabling all firewalls but it is still the same problem.
If I cant solve this...how do I uninstall windows defender? I hate getting the pop up about outdated definitions file on startup...