Microsoft announced that it has addressed a software flaw that recently led to false alerts appearing for a number of Windows users, indicating that the Microsoft Defender Antivirus program had stopped working, despite the fact that the protection was actually activated in the background.
According to what was reported by the “BleepingComputer” website, the problem emerged after installing a recent update package, as some users received warning notifications warning them of a program crash, which created a state of concern about the security of their devices.
Microsoft explained that the crisis was completely closed by launching update No. (4.18.26080.4) for the Microsoft Defender Antivirus program, which was officially released on September 17, 2026. The company confirmed that the appearance of the stop message does not necessarily reflect the disruption of actual protection on the affected devices.
In this context, the company called on users to download the latest update versions of the protection program, and to verify the security status in the field through the “Windows Security” application, and not be satisfied with the messages that pop up on the screen.
Users can check the protection status by going to the “Windows Security” settings, then choosing the “Virus & threat protection” section, while making sure to complete system and software updates to ensure the latest fix is applied.
If warnings continue to appear despite installing updates, the instructions recommend manually verifying that there are no conflicts with external protection programs or other technical problems that may have actually disabled the program, in order to avoid ignoring security alerts that may be real.
