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Firefox 66.0.5 won't load websites. At all.

  • 7 replies
  • 1 has this problem
  • 3 views
  • Last reply by Pepperrell

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I encountered problems with my LastPass add-in. I researched, updated Firefox to 66.0.5, and now it won't load any site. Internet Explorer does, unfortunately. I would prefer to use Firefox, but if it won't connect to secure websites, it seems.

"Did Not Connect: Potential Security Issue

Firefox detected a potential security threat and did not continue to citywire.co.uk because this website requires a secure connection.

What can you do about it?

citywire.co.uk has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site.

The issue is most likely with the website, and there is nothing you can do to resolve it."

Well, I guess that means that I can't use Firefox any more. Or have I missed something?

I encountered problems with my LastPass add-in. I researched, updated Firefox to 66.0.5, and now it won't load any site. Internet Explorer does, unfortunately. I would prefer to use Firefox, but if it won't connect to secure websites, it seems. "Did Not Connect: Potential Security Issue Firefox detected a potential security threat and did not continue to citywire.co.uk because this website requires a secure connection. What can you do about it? citywire.co.uk has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site. The issue is most likely with the website, and there is nothing you can do to resolve it." Well, I guess that means that I can't use Firefox any more. Or have I missed something?

All Replies (7)

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hi Pepperrell, a solution depends on the individual circumstances - can you please report back with those two pieces of information:

  • on the error page, please click on the "More Information" button. in the box that shows up now, what kind of error code is displayed?
  • under the error code there should be a "View Certificate" link, please click on it - what does the "issued by" section of this failing certificate say?

thank you!

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(a) SEC_ERROR_UNKNOWN_ISSUER (b) *.citywire.info

The page would load up until Friday last week. Monday was a public holiday and I was out of the office yesterday.

Other pages that won't load

- the FCA's (UK equivalent of SEC) Gabriel data reporting website
- the UK Government online website 
- Barclaycard's UK online site
- waitrose.com - no equivalent in the US

I can't help feeling that there's something wrong........

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That's sort of a strange issuer. I'm attaching a screenshot of what I see in the viewer when visiting that site. I suspect you have a "man in the middle" but so far we don't have enough information to know what it is.

When you get connection errors for nearly all secure sites, the problem usually is one of the following: Avast, AVG, BitDefender, Bullguard, ESET / nod32, or Kaspersky. It sounds as though yours is a bit more selective, but still we could optimistically consider whether the MITM is software you installed and trust vs. an intruder.

More info: How to troubleshoot security error codes on secure websites

Modified by jscher2000 - Support Volunteer

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We're using Bitdefender. Would you be able to explain to me how the problem arises? And if you are able, would you also explain how we should surmount it?

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Following on, I see the difference. In the bit you have outlined in red, I don't have what you have - instead, I have some Bitdefender stuff.

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Bitdefender is setting up as a proxy between Firefox and the web to check everything you retrieve. The above-linked article shows where the setting is to turn that off, but probably Bitdefender has a method to set up trust with Firefox (by adding its "signing certificate" to Firefox's cert9.db file) so you can use its filtering features. If that setup does not happen automatically at your next system startup, you could check with their support.

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Many thanks for that - we'll follow up with Bitdefender.