Every Avast antivirus (Free Antivirus, Pro Antivirus, Internet Security, Premier), even the free version, offers a great feature which can search for any viruses and malware on your computer before it even starts. It’s called a Boot-Time Scan and below are the steps how to perform it in the latest 2018 version. It works great even with the latest Windows 10 release.

Technically boot-time scan runs before the Windows are loaded, so it doesn’t give malware any chance to hide. From our experience we recommend running a full boot-time scan at least once a month, to make sure your computer is clean.

Quick Summary

  1. Open Avast interface and go to ‘Protection‘ » ‘Scans
  2. Select ‘Boot-Time Scan’ and click on ‘Run on next PC reboot’
  3. Restart your Windows and the boot-time scan will take place

Read more detailed steps and other options including screenshots below.

1. Schedule a Boot-Time Scan

Open interface of your program and navigate to tab ‘Protection‘ » ‘Scans‘ in the left menu. Once the scan overview shows click on ‘Boot-Time Scan‘ option.

Running a Boot-time Scan in Avast 2018 – Scan Overview

Running a Boot-time Scan in Avast 2018 – Scan Overview

On the Boot-time Scan window click on ‘Install specialized definitions‘ to add special virus definitions which detects malware on inaccessible places for Windows. Once done click on the green button ‘RUN ON NEXT PC REBOOT‘ and you are set.

Running a Boot-time Scan in Avast 2018 – Boot-time Scan

Running a Boot-time Scan in Avast 2018 – Boot-time Scan

Also, the message will change to ‘Scan will run on next boot‘. To cancel boot-time scan simply click on the ‘Cancel scheduled scan‘ link.

2. Advanced Settings of the Boot-Time Scan

For more advanced options click on the cog-wheel icon in the Boot-time Scan tile on the Other Scans overview (second screenshot in this article). In the boot-time scan settings you can select following options:

  • Areas to scan – All hard disks, only system drive, or auto-start programs
  • Heuristics sensitivity (analysis which detects not yet known viruses) – Off, low, normal, high (recommended though it may increase amount of false-positives found)
  • What do to do if a threat is found – Ask, move to chest, repair, delete, no action, or fix automatically
  • Others – Scan for potentially unwanted programs (PUPs), unpack archive files

Changing any of the settings or just confirming doesn’t make the boot-time scan scheduled. You still need to perform the steps above.

Running a Boot-time Scan in Avast 2018  – Boot-time Scan Settings

Running a Boot-time Scan in Avast 2018 – Boot-time Scan Settings

Please note the boot-time scan isn’t happening in Windows but before Windows are loaded. Below you can see the example of how the boot-time scan looks in the Avast antivirus 2016.

Running a Boot-time Scan in Avast 2018 – Boot-time Scan In Progress

Running a Boot-time Scan in Avast 2018 – Boot-time Scan In Progress

Your Windows will boot automatically if there is no virus found. If Avast founds a virus, you can perform one of the actions below by pressing a relevant number on your keyboard

  • 1 – Fix automatically
  • 2 – Fix all automatically
  • 3 – Move to Chest
  • 4 – Move all to Chest
  • 5 – Delete
  • 6 – Delete all
  • 7 – Repair
  • 8 – Repair all
  • 9 – Ignore
  • 0 – Ignore all

If the infected file is in the folder you also need to confirm the action by pressing

  • 1 – Yes
  • 2 – Yes all
  • 3 – No

You can always press ‘Esc‘ key to cancel the scan and continue with the boot. After the boot-time scan is complete, you can find its report in ‘Scan‘ » ‘Scan for viruses‘ » ‘Scan history‘. Alternatively, you can navigate to report by going to ‘C:\ProgramData\AVAST Software\Avast\report\aswBoot.txt‘.

Additional Notes

Although we have used Avast Free Antivirus 2018 screenshots in this article, these steps are also applicable for all Avast Antivirus solutions (i.e. also for Avast Pro Antivirus, Avast Internet Security, or Avast Premier) running the latest version available.

Steps are relevant for all Windows versions – Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10 (including Anniversary Update).

Written by Paul B.

My name is Paul and I love Avast since the Home Edition v4.8 (2008). I am recommending it to all my friends, but I realized they don't know how to use it. So I started this site in order to help others getting maximum from this awesome antivirus. Feel free to contact me via Facebook, comments below or this form.

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