It looks that there are problems with the certificate chain or the order of the certificates that are send (the intermediate certificate is send as the last in the chain).

• https://www.ssllabs.com/ssltest/analyze.html?d=www.competitionbureau.gc.ca

It might work if Firefox has cached the "Entrust Certification Authority - L1M" intermediate certificate by previously visiting a server that has send it. A server needs to send a correct certificate chain.

You can possibly save (paste) the "Entrust Certification Authority - L1M" certificate code in a .cer file and import this certificate in the Firefox certificate manager under the Authorities tab. Do not set any trust bits when prompted.

• Options/Preferences -> Privacy & Security
  Certificates: View Certificates

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

This issue occurs on several of my Firefox workstations as I have stated. Does this problem also occur for you when opening ?

https://www.competitionbureau.gc.ca/

A certificate chain is missing would cause FIrefox to flag this site as "unsecure" It would be nice to have a complete chain but I am not sure how it would consider it a security issue as the certificate must validate the site?

The certificate chain might not be missing, but the certificate list that is shown if I click the blue SEC_ERROR_UNKNOWN_ISSUER error text starts with the website certificate followed by the last intermediate certificate in the chain and then followed by the first intermediate certificate. These last two certificates are send in the wrong order, i.e. third certificate in the list (Entrust Certification Authority - L1M) should be send before the second certificate (Entrust Root Certification Authority - G2).

Firefox doesn't seem to see the second certificate (Entrust Root Certification Authority - G2) because it hasn't seen the third certificate (Entrust Certification Authority - L1M). This probably sounds confusing, but Firefox needs to see the certificate in the correct order, i.e. each certificate needs to chain to the next and this isn't possible when the order is wrong. If Firefox has cached both intermediate certificates from a previous visit to a server then Firefox can build a valid certificate chain and everything is fine. You can consider to contact the website and ask them to look into this issue and correct the order of the intermediate certificates.

• https://www.ssllabs.com/ssltest/analyze.html?d=www.competitionbureau.gc.ca

cor-el can you explain where you see "the certificate list that is shown if I click the blue SEC_ERROR_UNKNOWN_ISSUER error text "

Where is the blue sec_error?

If you click the Advanced button then you get more information about the error.

I now longer get a insecure connection with 65.01.

This was a problem with firefox

You probably picked up this specific intermediate certificate somewhere by visiting a website that send it to Firefox. If Firefox has cached this certificate then you no longer see this error like I posted above.