TheSystem requirements for macOS 10.15 Catalina are very similar to Mojave, with a couple of exceptions. Mojave supported mid-2010 or mid-2012 Mac Pro models with Metal-capable graphics processor
macOSCatalina 10.15 can upgrade Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks; macOS Mojave 10.14 can upgrade High Sierra, Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion; macOS High Sierra 10.13 can upgrade Sierra, El Capitan, Yosemite, Mavericks, Mountain Lion-KM Edit to add: These usually reliable links are just not Ihave tried to upgrade to High Sierra in the past as well (I have the 5.21gb installer in my Applications folder from Nov 20 2017) but I think whatever issue is affecting any macOS upgrade. I tried to upgrade to Mojave using the App Store "Open" method, it downloads and shows the progress bar, says 14 minutes, and then asks me to restart.Level8. 42,541 points. The App Store Updates page only informs you of updates available for the OS you are currently running. As you are running an older system then you are probably up to date on that system. If you want to install a newer OS that is called an Upgrade. The model and year of your Mac will determine which macOS you can upgrade to,
Anothermethod to solve the recovery server could not be contacted High Sierra/Mojave Catalina/Big Sur is to just quit the macOS installation process and select another time to do the job. You can use this method when the latest macOS has just been released because there should be many users are updating macOS, causing busy and crowded usage of .