Shield unreachable

Avast Free Antivirus / Premium Security
1

Avast Pro will not work. We get the error message: unable to start the file system shield. Shield unreachable

2

I had this same problem. After a lot of hair-pulling I figured out that you shouldn’t try to install Avast while in Safe MOde.

3

I suggest an installation from scratch:

  1. Download the latest version of avast! Uninstall Utility and save it.
  2. Download the latest avast! version and save it.
  3. Uninstall avast from Control Panel (if possible). If, for any reason, you can’t run it, try booting in Safe Mode and doing it from there. Anyway, boot after that.
  4. Run the avast! Uninstall Utility saved on 1. If, for any reason, you can’t run it, try booting in Safe Mode and doing it from there. Anyway, boot after you’ve run it.
  5. Install avast! using the setup saved on 2. Boot.
  6. Register your free copy or add the license key for Pro. Or even upgrade your key from old versions.
  7. Check and post the results. If, for any reason, you did not solve, try doing the step 3 in Safe Mode anyway.