Is your antivirus or similar extension causing the problem? Try making sure everything is up to date.

Check the date and time in the clock on your computer: (double) click the clock icon on the Windows Taskbar.

Check out why the site is untrusted and click "Technical Details to expand this section.
If the certificate is not trusted because no issuer chain was provided (sec_error_unknown_issuer) then see if you can install this intermediate certificate from another source.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

If "I Understand the Risks" is missing then this page may be opened in an (i)frame and in that case try the right-click context menu and use "This Frame: Open Frame in New Tab".

• Note that some firewalls monitor (secure) connections and that programs like Sendori or FiddlerRoot can intercept connections and send their own certificate instead of the website's certificate.
• Note that it is not recommended to add a permanent exception in cases like this, so only use it to inspect the certificate.

You can try to copy the cert8.db file from the "Old Firefox Data" folder on the desktop to the current Firefox profile folder.

• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can use this button to go to the currently used Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

Thanks very much cor-el. I worked through your answer. BTW when I use Chrome as my browser I can see the Firefox support site UI properly. I can also open g Mail)

The date and time are OK.

Using Firefox, when I try to open g Mail, the Technical Details under 'This Connection is Untrusted' do show that the certificate is not trusted because no issuer chain was provided. As I said, the 'I Understand the Risks' link is missing, but could not retrieve the certificate by your alternative suggestion since I don't know where the context menu is.

However, this is moot, since I was able to locate the profile folder using the Help menu and copied the cert8.db file from the "Old Firefox Data" folder on the desktop to the current Firefox profile folder. THIS WORKED!!!

A million thanks!!!!!!!!!

Let me add that not only can I open g Mail, but the UI in the Firefox support site displays properly

Were you previously able to check the certificate in the Certificate Manager via the "I Understand the Risks" section and check who is the issuer of the certificate?

It is likely that you had previously made an exception that got restored from the cer8.db file that you copied.

• Note that some firewalls monitor (secure) connections and that programs like Sendori or FiddlerRoot can intercept connections and send their own certificate instead of the website's certificate.
• Note that it is not recommended to add a permanent exception in cases like this, so only use it to inspect the certificate.

As I said, I was not able to check the certificate because the "I Understand the Risks" section wasn't there. So I guess I'll never know what happened for sure. (BTW I use Windows "Defender".  :) )

In any event, I am SO HAPPY that you fixed my problem!

I got the same message, and the text version of the Mozilla support site, and I copied the cert.db file from old outlook to the show folder in troubleshooting options, as prescribed. However, it did not work for me. Further, I can't get Sage reader to work, and Last pass has disappeared. How do I get Firefox to behave the way it used to; all I wanted was to get rid of the sluggishness? Thank you.

Hi gdubin

This issue can be caused by the computer time being wrong.

Check the date and time and time zone in the clock on your computer: (double) click the clock icon on the Windows Taskbar.

• https://support.mozilla.org/kb/Secure+Connection+Failed

Not the problem.

Hi gdubin

You can try to disable OMTC and leave hardware acceleration in Firefox enabled.

• about:config page: layers.offmainthreadcomposition.enabled = false

Maybe you should create a new thread instead of reusing this older thread.

Then you can provide more information like your operating system and installed extensions and installed plugins.

• [start a new thread]
• [/kb/Using+the+Troubleshooting+Informatio...]

Hi gdubin, the Reset feature removes extensions, so you may need to reinstall those. First, though, please check whether they are installed and you just need to move their icons onto an address bar.

To check whether they are installed, you can use the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then look for those extensions and make sure they are installed and enabled. (Disabled extensions cluster toward the bottom.)

If they are, then try the Customize feature to add them to the toolbar. This article has the steps for that: Customize Firefox controls, buttons and toolbars.

Any luck?

If the extensions are not listed on the Add-ons page, please refer to your LastPass and Sage documentation on how to push those into Firefox, as I suspect they are not available to install from Mozilla's Add-ons site.

Regarding SSL certs, if you made an exception for a site, please revisit that site and check the "Issued by" section of the certificate. This can help identify a problem with Firefox not being fully set up for your security software, as well as flagging up a possible malware issue.

To view the cert, click the padlock (or gray ! triangle) in the address bar, then More Information, then View Certificate. What do you find under "Issued by" for that site?

i did not read posts here, i just figured i make a suggestion, Refresh sometimes leaves old data behind, so its better to do clean uninstall & install firefox again & delete C:\Users\Ur User Folder\AppData\Roaming\Mozilla, delete mozilla folder from that location, i have Win8, it mite be bit different location in Win7 & it mite be same location, also look at the location where firefox was installed, in win8 its C:\Program Files (x86), just in case, if u see firefox folder delete it, but if C:\Users\Ur User Folder\AppData\Roaming & C:\Program Files (x86) are clean, no trace of Mozilla or firefox then u can install firefox again, if that dose not fix ur issue then there is issue between firefox & ur OS or firefox & some software u have, clean reinstall is always better cause u never know will refresh fix the issues u have or make them worse, if u go straight for clean reinstall u have less work

firefox has been in my PC long time, then i got waterfox & i uninstalled it recently, & a lot of waterfox issues were transferred to firefox, for 2 examples in mail box & steam community page some links did not work, refresh no help, if anything it added new problems, after i did clean reinstall all was fine, there was tons of small problems that were not big teal & new they are gone, the problem is there are a lot of old files left in C:\Users\Ur User Folder\AppData\Roaming\Mozilla\Firefox\Profiles\qgh92p1x.default-1424288549007, & this files & folders cause issues, some contain old settings, in my case waterfox settings, also there can be data corruption, in any-case the folders i mentioned half to be deleted or there is a chance ur issue wont be fixed un less its the other issue i mentioned, it depends, but my point is clean reinstall is better choice & less work

not gonna log in to sync neither, maybe it will download old data & i get the problems back

i wonder is it possible to clean sync server from my data, or does sync only work if i have 2 PC & both opened & then it transfers data to another Firefox in another PC? not familiar how sync works, the stuff i talk about above i have learned from using firefox

Note that it is best to use the Profile Manager to remove a profile if possible to remove the main profile in AppData\Roaming and the cache folders in AppData\Local

cor-el said

Note that it is best to use the Profile Manager to remove a profile if possible to remove the main profile in AppData\Roaming and the cache folders in AppData\Local

it can also be done by writing Mozilla in search when ur in ur user folder, easy to find profile folder, but i would delete Mozilla folder not just profile, profile is in Mozilla folder + there are more stuff there then just profile, this other files there can also contain problems, for example corrupted data, but profile removal is good suggestion, sometimes there is less work when u start from Zero, by that i mean reinstall & profile removal, tried other way & it was a lot of work without good results

Firefox uses two locations:

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\
• C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\