My iPhone 11 pro doesn't seem to be connecting to my computer. I figured I needed to update the OS. My iMac is the mid 2011 27" with plenty of space. MacOS High Sierra 10.13.6 is the latest compatible OS for my computer, but it is not found in the app store. How do I update?
iMac 27″, OS X 10.10
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,
Please use Safari to access the following link do not use Firefox
How to upgrade to macOS High Sierra - Apple Support
Before upgrading make a full back up of your Mac.
Check that third party apps you use have updates available for the new OS.
Check that your printers/ scanners etc have updated drivers and software available for the new OS.
Connect your mac to your router via cable rather than rely on WiFi.
Do not use your mac while it is downloading
and do not use any other devices that share the same internet connection.
If the App Store says Open then it is detecting a previous download of the install app
go to the Applications folder locate Install macOS High Sierra.app.
Move it to the Trash, empty the Trash.
Restart, click on the link again, the App Store should say ‘Get' or 'Download'.
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,
Please use Safari to access the following link do not use Firefox
How to upgrade to macOS High Sierra - Apple Support
Before upgrading make a full back up of your Mac.
Check that third party apps you use have updates available for the new OS.
Check that your printers/ scanners etc have updated drivers and software available for the new OS.
Connect your mac to your router via cable rather than rely on WiFi.
Do not use your mac while it is downloading
and do not use any other devices that share the same internet connection.
If the App Store says Open then it is detecting a previous download of the install app
go to the Applications folder locate Install macOS High Sierra.app.
Move it to the Trash, empty the Trash.
Restart, click on the link again, the App Store should say ‘Get' or 'Download'.
Don't use Firefox for these links...
https://support.apple.com/kb/sp765?locale=en_US
https://itunes.apple.com/app/macos-high-sierra/id1246284741?mt=12
If you get a corrupted message...
Naw, not damaged, it's just that you have an old copy already in Applications, there are 2 cures...
Disconnect from the Internet & set the Date back to 2014, then you can run the Install MacsOS High Sierra App in Applications, so expired Certificates are not expired.
Or... trash the Install MacsOS High Sierra.app in Applications then a new copy more recent version can be downloaded.
I have a mid 2011 iMac 27" running OS X Yosemite 10.10.5. macOS High Sierra 10.13.6 is not coming up in the app store.
