This certificate is signed by a untrusted issuer

Thanks for you response BD!

The issue has changed. I was able to change trust for my specific website to 'always trust' for this certificate.

However, even though I can display the website now just fine on Mac/Safari, this specific website will not accept my userid and/or password. So, I've referred the problem to the website help desk for a callback consult.

Here's what happens: iPhone 6s( iOS 13.4.1) uses my Apple KeyChain data to autofill and open this website page just fine.

However, the same KeyChain data autofill on my MacBook Pro(15inch, Mid 2009 OS X El Capitan Version 10.11.6) rejects login to the same website. Of course both, iOS 13.4.1 AND El Capitan Version 10.11.6, use the same Apple KeyChain data; indeed, when manually input via keyboard without engaging KeyChain on the Mac, login still fails.

That's a head scratcher because I figured I'd solved the Mac 'untrusted issuer' problem after the correct website displayed

again(after two weeks of trying).

So, I'll wait for the website account help desk callback to solve this problem. They'll probably just change my userid and password.

I tried to change them myself, but encountered a security question I don't remember setting so of course I DON'T KNOW THAT ANSWER!

Oh well; I'm not pulling my hair out yet. I know there's a simple answer, but I'll let the site tech support struggle with it.

Thanks again

Thanks BD!

I checked, iOS and Mac OS X El Capitan 10.11.6, for KeyChain passwords. They WERE the same in both iOS and OS X

login windows. But, your surmise that a old password was substituted via KeyChain proved true. I deleted old password,

reset password in KeyChain; my problem is fixed. Thanks for your insight about 'old or expired' KeyChain data.

CD