All HTTPS traffic is prevented from working

[REDACTED]

First, to set the stage, I am the founder of a computer consulting company that caters to end-users and small businesses, going on 30 years.

I have had this problem since about a week ago:  web surfing has had intermittent problems where pages will not load or will partial load.  On the same web address, sometimes I get a blank page, others I get a text rendering, others still I get a full load.  Refreshing the page will sometimes allow it to load, but mostly will not.  ALL downloads fail, Chrome stating a network issue.   I also discovered ALL HTTPS: traffic is prevented. 

I have tried Chrome, Firefox, both versions of IE (windows 10), etc.  ALL these problems are resolved by disabling AVAST web protection.  This was after days of troubleshooting and resetting/clearing cache etc as  you would normally attempt.

I installed AVAST on my mother's new laptop, and she called me yesterday stating she had a similar problem.  I asked her to disable avast and that ALSO fixed all her problems. 

It's been a week, and no google searches come up with this problem/resolution.  I didn't see any hits doing a quick search on the forum, but other than searching for HTTPS it would be a crap shoot. 

Latest program/antivirus installed, latest win 10 patches installed, rebooted etc.  I am using the free version, but was about to purchase licenses and I make recommendations for my clients who purchase directly with you currently.
Any suggestions/ advise before I uninstall and move to AVG?

thanks,
Robert

[Alikhan]

First, to let you know, Avast has purchased AVG and will be combining in the near future - https://forum.avast.com/index.php?topic=188195.0

Do you have any other security software installed?

I'd suggest doing a clean install to rule out a corrupt installation or any other cause.

1.Download your version of avast!, the avastclear tool and save them to the desktop:

Avast Free Antivirus
Avast Pro Antivirus
Avast Internet Security
Avast Premier

Download Avast Clear Tool

2. Uninstall Avast in Control panel  [If you don't have Avast in control Panel go to #3]
3. Uninstall in safe mode using Avastclear. [Running Avastclear is normal mode will give a prompt to go into Safe Mode]
Check : Once uninstalled check in device manager>view>show hidden devices if there is anything related to avast with a yellow triangle.. if so, uninstall it and reboot.
5. Install the version you downloaded.
6. Reboot.

Free: If you have the Free version, register the product for free for a year from the avast! UI.
Paid: If you have a paid license, insert the license key/activation code after the reboot at stage 6.

[REDACTED]

"Do you have any other security software installed?"
       Yes: Malwarebytes anti-malware, but it is only invoked when launched.

"I'd suggest doing a clean install to rule out a corrupt installation or any other cause."
      Seems a stretch since the other user called me with the same issue.  This is on a NEW laptop by a Sr. citizen used only for web surfing.  This is as clean as it gets.

The Software is registered.

PS. impressive response time!

[Eddy]

New laptop doesn't mean there isn't a av (or related software) pre-installed.

[Alikhan]

MBAM shouldn't cause a problem.

You could try a repair but I'm not sure if it will fix your issue:

Control Panel > Programs and Features > Avast > Uninstall/Change  > Repair.

Once the repair is done, you must restart the computer even if it doesn't tell you to.

[REDACTED]

New laptop doesn't mean there isn't a av (or related software) pre-installed.

It does if all traces of antivirus software were removed, both trial-ware and other bloatware - which this step was completed, rebooted, and installed Avast.  Thanks for verifying.

[REDACTED]

I ran the cleaner, rebooted, reinstalled.  I tried to log-in to my avast account FROM the avast program, and it failed to connect... wait for it... until I disabled Avast.

My Avast had been working flawlessly (other than being noisy) for months.  This is a recent change.

[DavidR]

Do you (or others with this issue) have a VPN application installed/running.

What happens if you just disable the https scanning in the web shield settings ?

I use firefox exclusively (current version 50.0.1) on three systems, XP Pro SP3, Win 7 SP1 and I have just got a new laptop (a day ago) running windows 10 and all are running fine for http or https sites.

My firewall is Agnitum Outpost Pro on the XP and win7 systems and the win10 firewall on the new laptop (no settings changed).

[Eddy]

As I am seeing quiet a lot of DNS hijacks lately I suggest to have someone look at Farbar log files.

[.: Mac :.]

Eddy is likely on the right track. Avast WebShield installs a Root CA Certificate to act as a man in the middle to be able to scan HTTPS traffic. If another service is doing the same it will conflict. Many adware programs are doing this type of redirection to inject ads in HTTPS traffic.

Suggest checking for Adware/PUP applications on the affected machines.

Also do you have a firewall/UTM device that does the HTTPS scanning (Example: SonicWALL's DPI-SSL feature?)

[REDACTED]

I do have VPN software that I use from time to time, but it has been installed and used for over a year, and this is a new problem.  Thanks for letting me know this is how it works.  Wouldn't reinstalling 'fix' the certificate issue? 

On the other machine that has this same problem, there is NO VPN software installed. 

I'm getting to the point of switching to another app since we have not found a solution.

[Eddy]

Are you using Windows Insider ?

[REDACTED]

yes, on my computer only.  The second pc is typical.  What is your thought?

[bob3160]

yes, on my computer only.  The second pc is typical.  What is your thought?

This should answer your question:
https://forum.avast.com/index.php?topic=156141.msg1351154#msg1351154
Insider preview and third party AV aren't a good choice at the moment. A problem that needs to be fixed by Microsoft.

[REDACTED]

Not sure that's correct - the user states he could not install the update until it was disabled. 

In any case, like I keep saying, the 2nd pc I have is standard win 10 machine.  Not insider preview either.

It's crazy to me to think this has been a problem for 3 weeks.   I will purchase another product, hopefully it wont have the same issue, if it does I'll let everyone know here.

cheers and thanks anyway!