"This connection is not secure"

Hi CommonSenseDesign, 

Is it a secure https:// url?  All the browsers are starting to get updated to show warnings for non-https sites.  The solution is to switch the site over to https.

Thanks for the reply, Dave.

Do you think it's necessary and/or advisable for a non-eCommerce site to switch to https from http? This is just a basic brochure site, without any secure information.

No, I don't think it's necessary, but it will produce those warnings.  So you could advise the client to either ignore them, configure their browser to not display them, or offer them the (billable) option to upgrade the site to https and get them an ssl certificate.

This page seems to indicate how to disable the warnings for Firefox: 
https://www.ghacks.net/2017/06/13/firefox-disable-this-connection-is-not-secure-warnings/

Hope that helps!

Also, I recently had to update a certificate and I tried the new free letsEncrypt.com service and it worked great.

If you use plesk you can install an extension that lets you automatically add SSL/HTTPS certifcates in just one click: 
https://www.plesk.com/blog/product-technology/lets-encrypt-plesk/

Or otherwise, you could ask your host if they support letsEncrypt.com or just install a certificate manually.