Avast 2015 Free blocking beta and nightly Firefox installers

I installed Avast yesterday. Whenever I try to execute beta or nightly Firefox installers, I receive error “Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.”

The latest stable Firefox 36.04 installer works as does following:

Installers which do not work:

The problem can be resolved by going to Avast settings → File System Shield → Customize → Scan when executing → Uncheck Scan programs when executing.

My OS is Windows 8.1.

You can report a possible FP here: https://www.avast.com/contact-us.php?subject=VIRUS-FILE

Except the error message says nothing about these executables being dangerous or is otherwise associated with Avast. It seems like Avast bug rather than false positive. Furthermore, component status in statistics does not report any viruses having been blocked.

  • Which version of Avast Free…?
  • Other security related software installed…?
  • Which AV(s) did you use before Avast…?
  • 2015.10.2.2215
  • No.
  • Windows Defender.

Hmmm, best you wait for one of the devs.

Just tried and have no problem with them. Firefox 36.0.4, avast free 2015.10.2.2215, ZA Pro 13.3.052.000.