On some of my servers, in the type section “Enhancement and security” it says errata 3 security advisories and 1 enhancement. However, it does not make any update operation. What exactly is this? I mean, why does it say applicable even though it makes these notifications on my servers. What exactly is this?
“Applicable Errata” are ones that are synced into your repos and that could be applied to the host, but that are maybe not yet in the appropriate Content View/Lifecycle Environment. If the host can actually install the packages, they should be listed as “Installable Errata”.
To install applicable errata, you will need to update your content views first and publish that version to the relevant lifecycle environment(s).
This section of the docs might also be helpful in understanding how this works.