Hi, separate security issue, update your Flash 27.0 r0 Flash Player Version: 29.0.0.171 Current Version https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, . . . .) Note: Other software is offered in the download. <Windows Only>

Try site after, Also if you are in the EU that could be the reason with new privacy law.

Try from their main page : https://www.ghostery.com/ https://adblockplus.org/

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

Thank you for the info. I did download a newer version of Adobe flash but It did not work. When I went to adplus.org, per your suggestion, I discovered that the owner of addons.cdn.mozilla.net configured their website improperly. So, to protect my info from being stolen, Firefox has not connected to this website. An exception for a certificate to this site is not possible because of HTTP Strict Transport Security which requires a secure connection. This may also be the problem when I try to download Ghostery. I hope that Mozilla can resolve this issue.

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

• uses an invalid security certificate SSL_ERROR_BAD_CERT_DOMAIN
• configured their website improperly

How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER

None of this appears to resolve the issue. I did get a "SEC_ERROR_UNKNOWN_ISSUER" message when I tried to down load Adblockplus. I can download on Edge so I do not know what to do now with Firefox. I guess that it is out of my control.

I called for more help.

You can check if there is more detail available about the issuer of the certificate.

• click the "Advanced" button show more detail
• click the blue SEC_ERROR_UNKNOWN_ISSUER message to show the certificate chain
• click "Copy text to clipboard" and paste the base64 certificate chain text in a reply

If clicking the SEC_ERROR_UNKNOWN_ISSUER text doesn't provide the certificate chain then try these steps to inspect the certificate.

• open the Server tab in the Certificate Manager
  • Options/Preferences -> Privacy & Security
    Certificates: View Certificates -> Servers: "Add Exception"
• paste the URL of the website (https://xxx.xxx) in it's Location field.

Let Firefox retrieve the certificate -> "Get Certificate"

• click the "View" button and inspect the certificate

You can see detail like the issuer of the certificate and intermediate certificates in the Details tab.

???? What is all of this? How do I even get to the "advanced" phase? I am not that pc savvy that I know what you are talking about. And, why should I do all of this? I had these add-ons working before. Then, Mozilla updated itself and now I do not have them anymore. How would I even know what a good certificate looks like?

Who do you call? What is the phone number?

This is a end user help forum not a support ticket line. Your confusing the two here. You should first remove all Addons and see what happens.

WestEnd, I do not think that your reply is appropriate. I posted a question to Mozilla and it was posted to this forum without any of my doing. By the way, "your" in your note should be "you're". As for removing add-ons. I have no add-ons! When Firefox updated, it removed all of my add-ons. I am trying to add add-ons that were previously installed but are now gone.

Please stick to the issue and try not to get lost in just trying websites, as you will likely encounter issues on various ones.

You were told that the SEC_ERROR_UNKNOWN_ISSUER error is likely a result of (any) security software intercepting connections. The way to prove this is usually to restart Windows in Safe Mode with networking enabled, which is the only reliable way of completely eliminating such software without uninstalling it (and not just disabling). If you don’t have security software installed, you will likely never see this error at all, unless something is really wrong with a website’s certificate, which is rare and would apply to just one website.

Then test in Firefox’s Safe Mode, so without add-ons, although I don’t expect your 2 add-ons to cause your issues so you could start Firefox in normal mode too. If that works as expected, reboot in normal mode and make sure to disable SSL scanning as documented. If that doesn’t do the trick, uninstall your security software, reboot, see what happens (all should be fine) and then reinstall the security software. Do note there may be more security-related software than what’s mentioned in the How to troubleshoot security error codes on secure websites support article. You should of course know what software you have installed.

If none of this helps: there should be an Advanced button as shown in Fred’s screenshot and support article. You could consider posting the full error message as well as the certificate content here. Have a look at this question for a similar issue and example of doing so. The step to import a certificate described there may not be necessary after reinstalling the security software.

PAL96815 said

I have no add-ons! When Firefox updated, it removed all of my add-ons.

It's possible those add-ons were not compatible and were removed. If you tell us what they were, we can check for you.

The removed add-ons were Ghostery, AdBlock Plus and one other that O do not remember. I cannot install any type od ad blockers with Firefox.

PAL96815 said

The removed add-ons were Ghostery, AdBlock Plus

Go to the Mozilla Add-ons Web Page {web Link} (There’s a lot of good stuff here) and search for what you want.

I cannot install any type od ad blockers with Firefox.

Why not? Is it the connection failure error?

In this instance because they are respected and trusted you can go to there home page and try installing from there :

• https://www.ghostery.com/
• https://adblockplus.org/

Note if you are in Russia the addon.mozilla.org page maybe blocked as well the above url's maybe blocked. If in the EU again because of new privacy law last week they also maybe blocked.

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

Been there. Done that.

Then attitude can be left at the door and if you are seeking help as per your post then please follow directions of the help given. You will get to a conclusion much faster. Please uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files , C:\Program Files(x86) & C:\ProgramData Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 60.0.1 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

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

PAL96815 said

I posted a question to Mozilla and it was posted to this forum without any of my doing.

Nothing on support.mozilla.org says you will be sending your question to Mozilla directly when you created the thread. Mozilla does not have the resources that would be needed to have call centres for one on one support by chat, phone or email, especially since it would be for free. Any products that have such one on one support options are generally for paid for products. Mozilla does not work with so called third-party support options either.

Besides here there is irc.mozilla.org with channels like #firefox , The Mozilla newsgroups and the long running independent forums.mozillaZine.org forums.