"Secure Connection Failed" for some web pages

[frank-brunner]

Please answer the following questions for yourself before submitting an issue

• [X] Filters were updated before reproducing an issue
• [X] I checked the knowledge base and found no answer
• [X] I checked to make sure that this issue has not already been filed

AdGuard version

7.18.1

Browser version

Edge, Firefox (always latest versions)

OS version

Windows 11, latest

Traffic filtering

• [ ] yes, I do

Ad Blocking

No response

Privacy

No response

Social

No response

Annoyances

No response

Security

No response

Other

No response

Language-specific

No response

Which DNS server do you use?

DNS protection disabled

DNS protocol

None

Custom DNS

No response

What Stealth Mode options do you have enabled?

No response

Support ticket ID

No response

Issue Details

I cannot open some web sites on my Windows machine when AdGuard is enabled. One of these web sites: https://dev.azure.com/. In the settings: When I disable all the features, like Stealth or DNS, but keep the main switch on the front page on, it doesn't work. When I disable the program altogether using the front switch, it works. I reproduced this with Edge (with and without plugin) and Firefox. The activity log does not report that anything got blocked. When I try to open the same web page on my Mac with the latest version of AdGuard installed there, it works nicely in Firefox, Edge and Safari, with all AdGuard features enabled.

Expected Behavior

No response

Actual Behavior

On Windows, Firefox says: Secure Connection Failed An error occurred during a connection to dev.azure.com. PR_END_OF_FILE_ERROR Error code: PR_END_OF_FILE_ERROR

And Edge says: Hmmm… can't reach this pageIt looks like dev.azure.com closed the connection Try: Checking the connection Checking the proxy and the firewall ERR_CONNECTION_CLOSED

Screenshots

Screenshot 1

Additional Information

No response

[AlexandrPkhm]

Hi @frank-brunner,

Could you please let us know if you are using Bitdefender AV software?

[frank-brunner]

I am indeed

[AlexandrPkhm]

@frank-brunner Judging by couple of posts on Bitdefender community (post 1 and post 2) it seems like this is a Bitdefender related issue.

Just to make sure, could you please try turning off Encrypted Web Scan in Bitdefender → Protection → Online Threat Prevention → Settings and let us know if the issue still persists after that.

[saturnotaku]

@frank-brunner Judging by couple of posts on Bitdefender community (post 1 and post 2) it seems like this is a Bitdefender related issue.

Just to make sure, could you please try turning off Encrypted Web Scan in Bitdefender → Protection → Online Threat Prevention → Settings and let us know if the issue still persists after that.

I can confirm this works on two different computers running Bitdefender and AdGuard with Firefox.

[frank-brunner]

I can confirm, works for me now as well. Seems you can't have it all. Thank you for finding this.

[Garlane]

I had the issue as well with the combination of AdGuard and Bitdefender, if you want to utilize both AdGuard and online threat prevention try adding the fake-ca certificate found in the folder \Program Files\Bitdefender\Bitdefender Security\mitm_cache\ to your certificates in your browser.

[Martinspire]

I had the issue as well with the combination of AdGuard and Bitdefender, if you want to utilize both AdGuard and online threat prevention try adding the fake-ca certificate found in the folder \Program Files\Bitdefender\Bitdefender Security\mitm_cache\ to your certificates in your browser.

This doesn't seem to work for me. Also it would be helpful (in case it works) if this was a suggestion in the settings. I would never have thought that Bitdefender was the culprit for something that only works when I disable Adguard