I am running Firefox version 124.0.2 on Windows 10 22H2. I am not running any Kaspersky product on my computer. I hope this helps.

Hi ixian, that RESET error indicates that the server (or a security service protecting the server) told Firefox to stop trying to connect.

You already tried many of the relevant actions. Could you also clear the site's cookies? Here's how:

On Settings page, Privacy & Security panel, Cookies and Site Data section, click the "Manage Data" button. This should launch a little dialog that allows you to remove cookies and offline storage data for the bank's site; you also could remove the data for any obviously related sites.

Any difference the next time you visit the site (in a new tab)?

Have a look at this. https://forum.kaspersky.com/topic/getting-pr_connect_reset_error-in-firefox-when-using-kaspersky-total-security-28248/#comment-116161

Try changing DNS over HTTPS (DoH) to "Off" or "Max Protection" and in Connection Settings change "Use system proxy settings" to "No proxy".

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile. Make sure you stay signed out of your sync account when testing.

Have a look at this. https://forum.kaspersky.com/topic/getting-pr_connect_reset_error-in-firefox-when-using-kaspersky-total-security-28248/#comment-116161

I do not have Kaspersky installed on my computer. Are you suggesting that I contact my Anti-Virus product support for the same ?

Hi ixian, that RESET error indicates that the server (or a security service protecting the server) told Firefox to stop trying to connect. You already tried many of the relevant actions. Could you also clear the site's cookies? Here's how: On Settings page, Privacy & Security panel, Cookies and Site Data section, click the "Manage Data" button. This should launch a little dialog that allows you to remove cookies and offline storage data for the bank's site; you also could remove the data for any obviously related sites. Any difference the next time you visit the site (in a new tab)?

I did that. I cleared all the cookies. Restart Firefox browser and still the issue persists. Please see the attached screenshot.

Try changing DNS over HTTPS (DoH) to "Off" or "Max Protection" and in Connection Settings change "Use system proxy settings" to "No proxy". Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile. Make sure you stay signed out of your sync account when testing.

I tried the following

1) Switched off DNS over HTTPS protection levels in Firefox to OFF. -Did not solve the problem. 2) Changed the Configure Proxy Access to the Internet in Connection Settings to OFF. -Did not solve the problem. 3) Created a new Profile and tried in that and then checked. -It worked.

Switched back to my default profile and the issue was still occurring. So I looked at the SSL certificate and in that I found that it was showing "Connection Not Encrypted." Please see the attached screenshot for the details. When I checked in Microsoft Edge i found that at the login page, where I get the PR_CONNECT_RESET_ERROR in Firefox, in Edge is shows me the Encryption as "Connection Encrypted (TLS_AES_256_GCM_SHA384, 256 bit keys, TLS 1.3)". But in Firefox it does not.

So this leads me to question why does the encryption not work only in Firefox and that too in the default profile? Should I delete all the profiles and then create a new profile? Or is this something else that is going on? Could it be an infection or a malicious extension/add on or something else?

Further when I started Firefox in safe mode, i.e. Troubleshooting mode, the issue still persists. So does that mean that the Troubleshooting mode, i.e. Safe Mode, is different than a new Profile mode?

Try renaming the cert9.db file in your profile folder while Firefox is not running so that a new one is generated.

Try renaming the cert9.db file in your profile folder while Firefox is not running so that a new one is generated.

Wow this worked. Thanks.

So how do I avoid this from happening in the future? Should I periodically flush my profiles and create a new profile? Or should I uninstall Firefox and then install a fresh copy of the browser from the website? Or do something else?

And more importantly what role does cert9.db plays? Is it a SQLite DB file?

The cert9.db file stores root certificates that Firefox trusts, plus certificates saved as you browse or that you import as trusted, plus personal certificates you may install (if you use any sites that require them). If Firefox doesn't find it, it will build a new one. I really don't know what in the file might have caused the RESET problem. That seems very random.