Avast is an antivirus program that scans your computer for virus-infected files. If you are getting the Avast boot scan error 42125 while scanning your computer, there might be a problem with installing the System Restore volume.
To fix this error, keep reading the instructions given below.
On your Windows computer, click the Start menu available at the bottom-left corner of the desktop screen.
Type ‘control panel’ in the search panel and press the Enter key.
From the search result, double-click the Control Panel app to launch it.
Alternatively, press the Windows + R shortcut keys to launch the Run dialog box.
Type ‘control’ in the Run dialog box and press the Enter key to open the Control Panel.
Click the System tab in the Control Panel window and select System Protection from the left-side panel.
If prompted, enter your administrator password in the required field and click Continue.
In the System Properties window, click the Configure button under the System Protection tab.
Select the Turn off system protection option and click OK to disable the System Restore feature.
Next, restart your computer and open the System Properties window from the Control Panel.
Click the System Protection tab in the System Properties window.
Select your device name under the Protection Settings section and click the Configure button.
Click the Restore system settings and previous versions of files radio button to enable the System Restore feature.
Click Create and create a system restore point.
After creating a restore point, restart your computer and rerun the Avast boot scan to check if the error 4125 has been resolved.
If the Avast Boot Scan Error 42125 persists, uninstall the Avast program from your computer and reinstall a compatible Avast product with the correct installation method.