Hello, Firefox was fine last week now it tells me the following for sites like Facebook, Google, etc www.facebook.com uses an invalid security certificate. The certificate is not trusted because no issuer chain was provided. (Error code: sec_error_unknown_issuer) On some I cannot bypass. The problem is I'm using Microsoft Family safety and the certificate issuer is now: Microsoft Family Safety. I don't know if this is caused by a Firefox update or Microsoft update, but either way Firefox now does not work, I cannot fix it and I'll have to stop using it unless there's a solution. I imagine the same fault is happening for anyone else using Microsoft Familty safety. I also use Chrome, which is even more pedantic about certificates, but Chrome works perfectly, suggesting it's a Firefox update that is shafting this. Any idea?