As soon as I installed the new version of the avast! antivirus on my Windows 8.1 PC, I started to have a strange problem. I could no longer access any of the websites over the HTTPS protocol. Trying to access even the known secure sites like Google and Yahoo showed me expired or invalid certificate errors. Assuming it to be some malware attack, I scanned all of my hard disk with avast! antivirus, and then with Malwarebytes’ Antimalware but could not find anything. After thirty minutes had been spent, I finally started to go through the avast! settings and figured out the culprit – avast! was set to scan HTTPS traffic and was injecting its own SSL/TLS certificate in place of the original certificates of different websites.
There are two solutions for this problem – either you allow the avast! certificate as an exception in various applications like Firefox, Chrome, Thunderbird etc., or you just disable the HTTPS scanning in avast!. The second method is much easier and you do not have to make changes in different applications individually. Here is how you can disable HTTPS scanning in avast! antivirus to fix the untrusted connection / invalid certificate / expired certificate errors :
- Double-click on the avast! antivirus icon in the Windows system tray to open the main avast! interface. You can also launch it from Start Menu or the Search Charms.
- In the avast! antivirus window, click on the Settings near the left-bottom corner.
- In the avast! settings window, select Active Protection from the left panel. Then click on Customize shown for the Web Shield module.
- Under the main settings for the Web Shield, un-check the checkbox that says Enable HTTPS Scanning and click on the OK button.
- That’s it. Now you can access various websites using the HTTPS protocol without any problem in any web browser.
Conclusion: Disabling the HTTPS scanning for avast! antivirus can solve some of the issues that you may have when accessing the secure websites over the HTTPS protocol. But at the same time, it makes your PC a little but less secure as avast! won’t be able to scan any malicious code being downloaded over a secure connection. If you do not want to disable HTTPS scanning, then you will have to add the exceptions for every secure website that you want to visit in a web browser like Firefox.