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Firefox certificates seemed to have corrupted. many sites blocked. html gone from help, ascii hyperlinks. flash gone. Had to reinstall windows to fix. What??

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  • Last reply by tsoilihoi

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Suddenly i got many errors that the site did not have a valid certificate and no connection (blocked). Google for one and firefox too. Mozilla help pages were ascii text hyperlinks not html pictures. Flash failed. I uninstalled the browser and cleaned out the registry and appdata of Mozilla entries and did a clean install. Still messed up. Ended up using a week old ghost image (acronis) to restore the partition back to last week. It works now. Other browsers worked fine, but firefox fell victim. I had even erased the cert8.db with no luck.

Just don't under stand why a reinstall wouldn't put it back. Glad I had an acronis image!

Suddenly i got many errors that the site did not have a valid certificate and no connection (blocked). Google for one and firefox too. Mozilla help pages were ascii text hyperlinks not html pictures. Flash failed. I uninstalled the browser and cleaned out the registry and appdata of Mozilla entries and did a clean install. Still messed up. Ended up using a week old ghost image (acronis) to restore the partition back to last week. It works now. Other browsers worked fine, but firefox fell victim. I had even erased the cert8.db with no luck. Just don't under stand why a reinstall wouldn't put it back. Glad I had an acronis image!

Chosen solution

Unless and until the ESET signing certificate is stored in Firefox's certificate store, cert8.db, Firefox is not compatible with ESET's filtering feature and will refuse to connect to any HTTPS address for which the fake ESET certificates are presented. This includes your requests for websites and Firefox's own connections, for example, to download the SafeBrowsing block list or to connect with Sync.

I don't know what happened to your system that caused the trust established in the previously working cert8.db file to be broken, but I can say (1) that happened and (2) now it's fixed by your having the ESET signing certificate stored as an authority in cert8.db again.

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What security software do you have?

There is security software like Avast and Kaspersky and BitDefender and ESET that intercepts secure connections and sends their own certificate or that incorporates special web shielding features that can block content.


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

  • click "Advanced" to expand the error message
  • click "Add Exception" to open "Add Security Exception"

If this isn't possible then open "Add Security Exception" by pasting this URL in the location/address bar and paste the URL of the website (https://xxx.xxx) in it's location field.

  • chrome://pippki/content/exceptionDialog.xul

Let Firefox retrieve the certificate -> "Get Certificate"

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

You can see details like intermediate certificates that are used in the Detail tab.

Who is the issuer of the certificate?

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I'm using Eset... However, I did a system restore, that failing,a clean install of firefox, deleting all appdata relating to Mozilla and registry data, local and user in the software section. It was still a problem in the RE install. Even deleted the cert8.db. What out took was using an acronis stored image from a week ago. That fixed it. I read a post about a toolbar that is installed outside the browser and wreaks havoc on firefox. I bet that's what it was. There were too many problems... Dallas was out to lunch, plain text hyper links in the firefox help section. Could not sign into firefox our use Google. I'll call eset tomorrow and investigate your suggestion with them. For now I think there was little left of firefox to sites that the browser was the very primary reason for it's malfunction. ALSO eset' logs were clean. Thx four your help.

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As you may know, ESET intercepts your browsing requests to filter them. To work with HTTPS sites, it needs to generate fake certificates so it can decrypt everything, and naturally Firefox rejects these as invalid until the ESET signing certificate is saved as a trusted authority in the cert8.db file.

I suggest making a backup of your working cert8.db file now in case this happens in the future, you can delete the live cert8.db file and use the working one in its place.

Or there is a procedure to manually import it in some past threads. (Since you do not need the info right now, I haven't searched for them.)

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So you are suggesting that i back up the current working cert8.db and use it if there is a future corruption caused by eset? Please follow my logic... I deleted everything relating to Firefox and reinstalled... would not things have started all over again fresh and eset would not have problems with the likes of google or firefox sites themselves? Also how would the certificates negate my flash and cause plain text hyperlinks to show up in the firefox help. seems to me a site tried to load a bogus flash program but instead installed something on the system (win 10) which targeted firefox. But if this indeed is a problem with Eset, maybe I should start using windows defender that is built in. I need to call them, tomorrow. Any thoughts on my suspicions?

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Hi tsoilihoi, if your Firefox is currently working with ESET filtering, then it must contain the ESET signing certificate.* This certificate does not exist in a fresh install of Firefox, or in a new profile, and also would be removed by using the Refresh feature. Of course the certificate can be reinstalled by ESET (perhaps by restarting Windows?) or by manual import, but having a copy of the file would be a shortcut to getting it back in there.

* If you want to check:

Open the Certificate Manger as follows:

"3-bar" menu button (or Tools menu) > Options

In the left column, click the "Advanced" button, and on the right side, the Certificates mini-tab.

Click the View Certificates button to open the Certificate Manager, and then select the Authorities tab. This should have a very long list of trusted signing certificates. Can you find one for ESET?

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yes, attached...

Can we account for the different messages; Firefox reporting that it is blocking connections to account.google.com and account.firefox.com, including the inability to sign in to Firefox sync. Flash stopped working and as I mentioned, the help section of Firefox rendered as plain hypertext.

Just before the problem started, I clicked on a movie at a questionable site and a dialog box asked me to download flash... It is pulsing like it was downloading and I killed it fast and high tailed out of there....

As I had mentioned, there was talk on another chat about a browser bar being installed and finally removed in the remove programs area of windows. They stated, there that I caused certificate corruptions.

I do not know the veracity of this line of explanation.

I am wondering why a clean install and system restore didn't straighten out the problem unless the culprit was in an area not touched by system restore or a clean reinstall of Firefox.... Leading to a fix caused by overwriting the whole drive with an older image.

My concern is that ESET just came out with a new version and perhaps it is certificate mishandling that caused the problem. Your thoughts?

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Chosen Solution

Unless and until the ESET signing certificate is stored in Firefox's certificate store, cert8.db, Firefox is not compatible with ESET's filtering feature and will refuse to connect to any HTTPS address for which the fake ESET certificates are presented. This includes your requests for websites and Firefox's own connections, for example, to download the SafeBrowsing block list or to connect with Sync.

I don't know what happened to your system that caused the trust established in the previously working cert8.db file to be broken, but I can say (1) that happened and (2) now it's fixed by your having the ESET signing certificate stored as an authority in cert8.db again.

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I'll place a copy of the cert8.db in my backup area. In addition it is retrievable from an Acronis TIB backup.

I'm going to talk with ESET because the version 9 is only a week old and its something they will be aware of or should be made aware of.

thanks Jscher2000 and others.

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I read a Firefox article mentioning Eset and ssl checking... Attached is a setting that I turned off dealing with https scanning.

I'll call in the morning and see if Eset has had problems with this activity running on a regular basis.

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I verified that the certificate problem is a known issue with the new ESET version 9. I'll post the settings changes when I get them. unchecking https scanning seems to be one of them.