Browser Cleanup Tool in Avast Antivirus which was supposed to check and warn of bad add-ons and toolbars in browsers has automatically deleted add-ons in Firefox browser for some users. A bug ” in the component calculating hashes of the extension packages cause (only in some rare cases) deletion of the wrong file – the original instead the packed one ” is the reason for this.

Avast team has identified this issue after reported by users in their forum, and the fix has been already sent via a VPS update.

VPS Update fixes the Browser Cleanup Bug

Avast’s response

” We identified BrowserCleanup to be the cause. An update in a hash calculation mechanism caused the wrong files to be deleted instead of some temporary files. Unfortunately QA processes did not catch the problem as it affected .XPI extensions in Firefox only (which were not fully covered by the tests).” Avast’s team member Tosal said in a thread.

Avast Browser Cleanup havoc

Fix: Firefox crashes due to Avast 2015 [Updated]

This could’ve been automatically installed for you by now, you don’t need to do anything from your end, ensure virus definition or VPS version showing this number : 14118-0.

For that, open Avast interface > Settings > ‘About Avast’ and check the virus definition version number, it should match the above one.

How to avoid the install of Browser Cleanup Tool while installing Avast?

When you start the free antivirus installation, instead of the regular installation, choose ‘custom’ method, uncheck Browser Cleanup and proceed with the installation, it won’t be installed. If you’ve already installed Avast with BC, then follow the below instructions to disable or remove it.

Disabling: Open Settings > Tools > Click on ‘Customize’  for ‘Browser Cleanup’ and untick ‘check my browsers regularly for toolbars with bad ratings’, click ‘Ok’ to apply the changes, you can even turn it off from Tools in Settings.

For more details, read: How to disable GrimeFighter and Popups of Browser Cleanup in Avast?

Uninstalling:  Control Panel > Programs and Features > select ‘Avast Free Antivirus’ and click on ‘Change’, when the setup dialog opens, continue to the next step, remove tick mark for ‘Browser Cleanup’ under ‘Tools’ and click on ‘Continue’. BC will be uninstalled, you may need to restart your computer for the changes to take effect.

deselect Browser Cleanup component

Update: Added the screenshot.

Similar article: How to Uninstall GrimeFighter from Avast?

Are you affected? Which add-ons it has deleted? Do you use this tool in future? Let us know in the comments.