Problems with secure update 2020-004

[Rhino_60]

Is available from App Store an upgrade (SecUpd2020-004) for my High Sierra 10.13.6 OS system.
I've downloaded it and after reboot (... the upgrade requires reboot), the upgrade has been created a new disk called "MacOS Installer" that try to reinstall High Sierra (into a new partition...?!).
I must interrupt the installation from switching off rear button, restart system holding ALT and reselect the original startup disk, but the upgrade has no successful.
Has anyone the same problem?

 

[LuisN]

Is available from App Store an upgrade (SecUpd2020-004) for my High Sierra 10.13.6 OS system.
I've downloaded it and after reboot (... the upgrade requires reboot), the upgrade has been created a new disk called "MacOS Installer" that try to reinstall High Sierra (into a new partition...?!).
I must interrupt the installation from switching off rear button, restart system holding ALT and reselect the original startup disk, but the upgrade has no successful.
Has anyone the same problem?

You must let the computer boot from the MacOS Installer partition or it will not update.