Apple has changed the requirements regarding HTTPS server certificates in its products – Mainly Catalina 10.15 and iOS 13.
SHA1 signed certificates are no longer considered secure and servers using them will be blocked.
The default CA certificate we generate for HTTPS Inspection is SHA1 signed.
This means end users with a default HTTPS Inspection CA certificate using macOS 10.15 endpoints will encounter an untrusted certificate error message.
More details (and a solution) can be found in sk163932.
In R80.40, the default HTTPS Inspection CA certificate will be SHA256 signed.
This change will also be integrated into upcoming Jumbo Hotfixes for other R80.x releases.