An update to Windows Defender (virus definition update) released by Microsoft this week is ruining Security Essentials and Windows Defender in Windows 7 and 8.1, according to reports.
This update adds digital signatures to new viruses (1.289.1521.0 version) in the Microsoft security application, but seems to have created more harm than good. Too many users confirm that after installing this version, real-time protection has been disabled and Windows security applications are warning that malware updates are out of date.
If you try to perform a manual scan on the computers that installed the update, it will fail by displaying the 0x800106ba error. So neither Microsoft Security Essentials nor Windows Defender can detect and remove malware.
According to Mary Jo Foley by ZDNet, Windows 10 is not affected by the error and Windows Defender is running correctly on this version of the operating system.
Microsoft acknowledged the problem and said it is promoting a new update to fix it. However, the company claims that only Windows 7 and Windows Server 2008 are affected, although there are many reports also for Windows 8.1 devices.
The company has not officially stated that the virus definition update is the fault, but the new version is 1.289.1588.0.