In the Security Alert dialog box, click View Certificate.
Alert "The certificate issuer for this site is untrusted..."
"Certificate issuer untrusted or unknown" security alert
When signing in to an Adobe application, you receive the following alert:
This page requires a secure connection which includes server authentication. The certificate issuer for this site is untrusted or unknown...
Solution: Install the GlobalSign Root CA certificate
Adobe sign-in and activation processes require the GlobalSign Root CA certificate. Here's how to install it.
Click the Certification Path tab, and select GlobalSign Root CA.
Click View Certificate.
Click Install Certificate.
When you are prompted for an installation location, select Trusted Root Certification Authorities. Continue with the wizard, and then click Finish.
Close the security alert and click Retry.