This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Why is Firefox now blocking access to sites including accounts.firefox.com citing "invalid security certificate"

more options

Since the last update Firefox is blocking access to sites like Facebook and Google citing "invalid security certificate". It asked me to log on but blocked that too as accounts.firefox.com also has an invalid certificate apparently. What is going on?

Since the last update Firefox is blocking access to sites like Facebook and Google citing "invalid security certificate". It asked me to log on but blocked that too as accounts.firefox.com also has an invalid certificate apparently. What is going on?

Chosen solution

hi Leatherdale, unfortunately this is likely due to your avast/avg security software tampering with encrypted connections. please either try to reinstall your security software or else follow the more specific steps for it at How to troubleshoot security error codes on secure websites.

Read this answer in context 👍 1

All Replies (3)

more options

Suluhisho teule

hi Leatherdale, unfortunately this is likely due to your avast/avg security software tampering with encrypted connections. please either try to reinstall your security software or else follow the more specific steps for it at How to troubleshoot security error codes on secure websites.

more options

Thanks very much. I use AVG and I suppose it was one of their updates that was causing the problem. Anyway I found and unticked the "enable HTTPS scanning" which seems to have done the trick.

more options

I had this problem just after a Firefox update. All sites I tried to get onto including anything via Google and Firefox itself was blocked. As an AVG user I tried the advice above (which I accessed via a different browser) but it failed to fix the fix the problem. I then uninstalled AVG driver scan, started to remove AVG itself but when it offered me the option of repair instead, took that. It seems to have done the trick, fingers crossed!