Separate Security Issue: Update your Flash Player Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version: Version 28.0.0.126

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

http://kb.mozillazine.org/Error_loading_websites

Thanks for these links, Fred. I tried all this but it doesn't appear to help. I turned off ipv6, flushed the cert.db, and so on. The problem appears to be that Firefox is not findinf the SSL cert for specific websites: My.yahoo.com is missing its cert and the permission window doesn't allow me to get one, it just says there isn't one, while its sister page mail.yahoo.com has a valid cert and therefore works in https:

Ya I checked both pages. Missing the padlock.

Please : https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer and https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles then https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings TEST....... If no issues then Extensions which need to be added back in 1 at a time and tested ..... Or it is your Profile : Make a new one and test ...: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Note: Any customization will revert back to default, you will also need to reinstall Extensions.

Please let us know if this solved your issue or if need further assistance.

OK, took some time to undertake all the items in the list above. No change, but a couple more clues:

Clearly, there is a problem with my profile. I can access my.yahoo.com on other computers, and can login there without issues. It is only on this particular laptop that the problem resides.

Furthermore, the strange thing is that I can't go to my.yahoo.com directly (if I do, I get "The connection to my.yahoo.com was interrupted while the page was loading. The page you are trying to view cannot be shown because the authenticity of the received data could not be verified." But I can get to it indirectly: If I go to yahoo.com (which loads fine and shows a cert), I can then add "my." to the URL and get to my.yahoo.com, which then shows its cert.

But if I reload that page, I get the error again!

I checked the cert, and it is from Digicert, has not expired. I tried flushing the cert8.db and cert.override.txt files, and I also made sure the system date on my computer is correct. No effect.

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Type about:profiles<enter> in the address bar.

Fred, thanks for your help, and thanks to Pkshadow as well: Finally tried to delete my profile, create a new one, and try to navigate to my.yahoo.com....and still got an error: Site unable to load! So I added an exception to my network filter (littlesnitch on macos had been added to try and limit/monitor access to my computer by malware and any intruders), and now the site loads fine. Hard to believe that the netwok filter blocked access to this site and no other! Anyway, I would not have figured this out unless you had helped me eliminate the other possibilities, so thank you very much!

Glad to help. Safe Surfing.

Contact littlesnitc and ask about it.

I'm having the same problem too. Can't visit Amtrak website (www.amtrak.com). Gives "secure connection failed" message. Tried clearing cookies, disabling antivirus, nothing works. The site loads and works just fine in other browsers.

This is a problem many others are having, do a search for "cant visit amtrak website in firefox" and you'll see.

I submitted feedback to Mozilla about this, hopefully it will be addressed in the next version, until then, I'll just use Edge.

ChuckMozil Please go to the top of any support.mozilla.org web page and use the Ask A Question link; https://support.mozilla.org/en-US/questions/new Select the product for what the problem is (Firefox or whatever).

Now select the category for the problem. At the bottom is Other.

Describe the problem in brief (one line). Then press <enter>. The website will display any prior posts that might help you. If nothing on the list can help, at the bottom press the button; None Of These Solve My Problem.

Now enter all the relative information on the problem. At the bottom of this, you can Add Images.

Under this is Troubleshooting Information. Please press the Share Data button. This will let us look at your system details. No Personal Information Is Collected.

FredMcD

I did that yesterday, you can see my question here: https://support.mozilla.org/en-US/questions/1218697 and I did select "share data"

As you can see in that thread I've tried some other steps since then and nothing has worked.

Thanks for your help.