Yahoo Mail Expired Security Certificate Apr 6, 2005. One cause of Invalid or Expired Security Certificate errors is a problem with. One cause of Invalid or Expired Security Certificate errors is a problem with.

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.

1. The Apple Mac OS X operating system produces electronic certificates when a user attempts to connect to wireless networks or other services that require authentication.
2. Using Mozilla Mail, I receive 'Mail Shield Security Exclusion' pop-up from Avast when attempting to access e-mail via POP. The pop-up goes on to state that certificate has expired (like within the last 24 hours it would seems) but when I view the certificate it actually expired 2016-12-09 (issued by Symantec Class 3 Secure Server).

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'.

Mac Mail Problems

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

How To Update Expired 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.

I recently had to restore from a system image (full restore of C: drive where my program and system files are kept, no changes to D: so my personal files weren't reset, and probably some temp files and preferences weren't either) and after doing so, and then reinstalling avast onto this system image (the image was made at a time when I had a different antivirus) I encountered a problem with firefox which seems to be something to do with conflicts with it and avast.
Immediately after the system imaging firefox worked fine, and immediately after avast's installation avast worked fine too. The I updated both of them to the latest state, restarted and logged back on. This time when I opened avast to go to google I got a warning about a certificate on google's page being unrecognised (Unfortunately I can't remember the exact wording), But I was able to follow some of the options on the dialogue brought up by firefox and see a certificate related to avast was causing the issues. I tested by temporarily disbaling avast's web and mail shields and opening firefox again, that time it went to google.co.uk without issues. I turned the web and mail shields of avast back on and I got the same certificate problem again.
Eventually I used the 'I know the risks button' in firefox and created an exception, which I think might not have been the best way to solve this. Because I still had problems loading other https pages (for exmaple the links to google plus or gmail from the google home page). I am now rather confused as to what settings my browser has for certificates, and think they are probably the wrong ones, although at present google is able to load. I also did something involing removing some certificates from 'firefox sandwich button'-->options-->advanced-->view certificates, I don't know if this helped or made things worse, I can't remember precisely what I did.
I haven't installed avast's browser cleanup tool, so it can't be responsible, I have disabled avast's plugin in both FF and chrome so it isn't the problem, And this issue hasn't occured in chrome at all, just FF.
So my current situation is that firefox seems to be loading pages again, chrome was never affected, avast currently has those shields turned on, no avast plugins have been active in the browsers or are currently active. But I think my certificate list might be in quite a mess.
Firstly, can anyone explain the precise causes of what happened here?
Secondly, please can someone tell me how to get my certifcate settings back to what they should be? I want them back to what firefox should have, I don't know if these are the same certificates as can be controlled through the option which is brought up when searching for 'certificate' in control panel. I don't know if avast added one, or took one away or something, and whether this is thr right configuration to have. I also don't know quite why only firefox was affected and not chrome (I didn't test IE, I never open it). I would like to set firefox's (and perhaps the whole computer's) certificates back to the normal setting, but don't want to have to do a system image again to run the whole computer back, and don't want to reset firefox in a way that will wipe out all my extensions and all my settings, I just want to reset my certificates, I don't think there is anything wrong with any of my other settings in firefox. If I had to reset (or uninstall and reinstall) firefox entirely that would be difficult as it might take quite a while to return all my settings to the way I like them (settings like: which plugins are enabled/disabled, what happens to different file types when I download them, which buttons are and aren't on the various bars within firefox...) and reinstall extensions and everything. I would hope there was a way to just set the certificates (and anything that is directly linked and follows on from them) back to defaults. Does anyone know how, all I could find on google was stuff about full resets of all settings and extensions. Also If I reset the certificates how will I know when they are correctly reset and how will I know none have stayed in place which shouldn't be, how can I check?
Thirdly: if this ever happens again what should I do? I don't think i followed the best route this time, I was tired and had never seen this kind of certificate security warning before. With the outcome of both having firefox work properly and having avast's web shield (mail shield would be helpful also but I'm not sure if it's relevant to me, I do all my mail through gmail accessed through either browser)running. What needs to be done?
Apologies for the probable repetition of certain things in the post above, it's late where I am and I've just spent ages struggling with a series of dodgy windows updates, then full failure of windows update itself, then a system image, then reinstalling things and then this happened. The windows updates issues aren't a matter for this thread, I think I fixed them by going back to a system image but I've still got to go through the list again and try and install all those I can, trying to work out which caused the issues so which not to try installing this time.
Thank You

Mac Email

Edited by rp88, 13 May 2015 - 07:17 PM.