avast mobile virus definitions update failed

Based on our analysis of available data, we are now lifting the AV compatibility check for the March 2018 Windows security updates for supported Windows 10 devices via Windows Update. Our recent work with our anti-virus (AV) partners on compatibility with Windows updates has now reached a sustained level of broad ecosystem compatibility. We recommend customers check with their AV provider on compatibility of their installed AV software product. We are lifting the AV compatibility check for Windows security updates for supported Windows 7 SP1 and Windows 8.1 devices via Windows Update. We continue to require that AV software be compatible, and in cases where there are known issues of AV driver compatibility, we will block those devices from updates to avoid any issues. To help prevent these stop errors, Microsoft is currently only offering the January and February 2018 Windows security updates to devices that are running antivirus software that is from antivirus software vendors who have confirmed that their antivirus software is compatible by setting a required registry key. These calls may cause stop errors (also known as blue screen errors) that make the device unable to boot. The compatibility issue arises when antivirus applications make unsupported calls into Windows kernel memory. Microsoft has identified a compatibility issue with Microsoft's Windows security updates released in January 2018 and a small number of antivirus software products.

Important: Windows security updates and antivirus software Overview

Avast mobile virus definitions update failed