The table below has some common error codes from Microsoft Security Essentials. You can also try searching the Microsoft Community Forums for help.
|Error code||Possible reason for error||What to do now|
|0x8004ff00||Another Windows installer may be running.||See I can't install Microsoft Security Essentials for more details.|
|0x8004ff06||You may have a newer version of the software installed.||You need to uninstall all versions of the software. The following articles can help you uninstall a program:You should then reinstall your program.|
|0x8004ff81||Malware may be stopping your security software from installing correctly.||Download and run Windows Defender Offline.|
|0x80070002||There may be a problem checking for updates.||See Windows Update error 80070002 for more details.|
|0x80070005||You may not have the correct privileges to continue with this action - you may need to log on as an administrator.||See Installation error 0x80070005 for more details.|
|0x80070490||Malware may be stopping your PC from installing or running updates.||Download and run Window Defender Offline.|
|0x80070643||This is a generic error code - there could be an undiagnosed problem with your security software.||Try uninstalling any other security software. Also see Community answer Installation error 0x80070643|
|0x80073b01||This is a non-critical error. Your PC is still protected.||Restart your PC or reinstall your security software.|
|0x80248011||There is an issue with the file on your PC that stores updates.||See error 0x80248011 for more information.|
|0х80508023||Malware may be stopping you from scanning your PC.||Run the Microsoft Safety Scanner then update your security software and try again.|
The table below has some common error codes that you may get when using other Microsoft security software. You can also try searching the Microsoft Community Forums for help.