Windows 10, starting with version 1803, includes Windows Defender Exploit Guard, a new security layer in addition to the standard Windows Defender Antivirus.
Among other features, Windows Defender Exploit Guard has "Controlled folder access" option that prevents modification of key system and user folders that it thinks might be malicious or suspicious.
In some cases "Controlled folder access" option may conflict with Acronis software, for instance, it can cause errors 2902, "There was an error creating a temporary file that is needed to complete this installation" when trying to install Acronis True Image.
Update March 11th, 2019: the issue with failing installation of Acronis True Image has been fixed on Microsoft Windows Defender side. Just install all available Windows updates to fix Acronis True Image installation failure.
If Windows is up-to-date already, but Acronis True Image still fails to install, proceed with temporarily deactivating the conflicting Windows Defender component as explained below.
This section explains how to temporarily turn off "Controlled folder access" option.
- Open Windows Start menu.
- Type Windows Security.
- Press Enter on keyboard.
- Click on Virus & threat protection on the left action bar.
- Scroll to Ransomware protection on the right side on the screen.
- Click Manage ransomware protection.
- Click the toggle button to turn off Control folder access option.
- Click Yes to confirm the change, if prompted.
- See if this resolved the issue with Acronis software.
- To turn back on the option "Controlled folder access", click the toggle button again.