You can check to see which updates have correctly installed for macOS.
While macOS upgrades should always proceed in a sequential fashion, sometimes things go awry. Typically, the Software Update preference pane shows all updates available for your current release of macOS, and when installed, they disappear from the list.
However, I recently had a crash during an update that left me confused as to whether a security fix was installed or (based on errors) the whole thing had gone pear-shaped. Software Update showed no outstanding items to install, but I wanted to be sure.
Fortunately, there’s a way to review your system upgrade history, though you may have never needed to dig it up before:
- Hold down Option while choosing the menu and select System Information.
- Click the Installations link under Software in the left-hand list.
- Scroll down under Software Name to find macOS, and you can look through a list of all updates ever installed on the system.
Read more at MacWorld.com