This article explains how to temporarily turn off Windows Defender Antivirus in case it conflicts with Acronis software on Windows 10, e.g. prevents successful software installation or update/upgrade.
If you want your Windows machine to turn off automatically after completing the backup job, you can set up automatic shutdown using native Windows commands.
Solution
Acronis Cyber Backup 12.5: in the backup plan, open Backup options -> Pre/Post commands,
Acronis Cyber Protect 15, Acronis Cyber Protect Cloud: in the protection plan, go to Backup module, then to Backup options -> Pre/Post commands,