Microsoft has admitted that Windows 10 will sometimes shut down third-party anti-virus software after the OS is updated, but only does so temporarily.
The clarification from a Microsoft executive follows security company Kaspersky filing an antitrust complaint against Microsoft with the European Commission in June. At the time Kaspersky claimed that Microsoft was "fiercely" promoting its own Windows Defender anti-virus, at the expense of competitors' security software.
While Windows 10 will sometimes disable third-party anti-virus software after the OS is upgraded, according to Microsoft partner director Rob Lefferts, he described the shutdown as short-lived, and said it was necessary to correctly upgrade Windows systems when third-party software wasn't compatible.
"We built a feature just for AV apps that would prompt the customer to install a new version of their AV app right after the update completed. To do this, we first temporarily disabled some parts of the AV software when the update began," wrote Lefferts, who is part of Microsoft's Windows & Devices Group for Security & Enterprise.
"We did this work in partnership with the AV partner to specify which versions of their software are compatible and where to direct customers after updating.
"We believe in honoring customer choice and supporting a rich security ecosystem."
Lefferts adds that Windows Defender will only take over from a third-party AV service when the licence to that service expires.
In his post, Lefferts' also addresses another complaint by Kaspersky, that third-party security vendors don't have enough time to ensure their software is compatible with new versions of Windows 10.
"Months before a semi-annual update is delivered to customers, interested parties can get easy access to fully running and deployable versions of the release, stay current with updates as the release progresses and becomes feature complete, and provide timely feedback on issues and bugs," he said.
"Also, because AV software can be deeply entwined within the operating system, we doubled down on our efforts to help AV vendors be compatible with the latest updates."
Microsoft will release two major feature updates for Windows 10 this year, with the next being the Fall Creators Update in a few months time.
Regular preview builds of Windows 10 are made available for anyone to test via the Windows Insider Program, and often contain new features months before they are made available to the general public.
However, Kaspersky CEO Eugene Kaspersky claims that the final Release to Manufacturing (RTM) version of Windows 10 that is released to the public can differ significantly from preview builds, and that Microsoft needs to share RTM builds at an earlier stage.
The Russian firm also alleges that Windows 10 prevents Kaspersky software from clearly notifying customers when their licence is about to expire, complaining about being obliged to use Microsoft's Action Center. In contrast Lefferts said that Microsoft has: "worked with our AV partners to build a consistent set of notifications to inform customers if their license is about to expire and to present options to renew the license".
Recent independent reviews of Windows Defender rated it as competent but not as good as some third-party security software.
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Nick Heath is chief reporter for TechRepublic. He writes about the technology that IT decision makers need to know about, and the latest happenings in the European tech scene.