https://wccftech.com/windows-10-1803-blocks-avast/

Windows 10 versions released in 2017 – the Windows 10 Creators Update and the Fall Creators Update – made us hopeful that Microsoft may have finally found a system that deals with a majority of bugs before a new version is released to the public. While those two versions weren’t free of all the bugs, the issues weren’t as widespread. However, Windows 10 April 2018 Update is reminding many of the early days of Windows 10 when every new version ended up breaking machines or brought some migraine-inducing compatibility issues.

After multiple user reports, Microsoft confirmed earlier this month that the latest version has been blocked on Intel and Toshiba SSDs. It now appears that the Redmond software giant is blocking Windows 10 installation on systems running Avast antivirus software, as well.