I have an iMac, vintage 2012, that was running High Sierra. I needed to erase the HD because it started having issues (running super slow), and I reinstalled the OS through Recovery Mode. Unfortunately, it went back to its original OS, Mountain Lion. Now it won't let me upgrade from Mountain Lion to High Sierra. I've tried downloading Mountain Lion but the dmg file won't open and it won't let me access it through the App Store. Help!
iMac 21.5″, macOS 10.14
Welcome. You could try upgrading to El Capitan first…
Welcome. You could try upgrading to El Capitan first…
Thanks for responding so quickly! I just tried it and I am unable to access the App Store from the iMac (directly or through Safari). I'm responding on my MacBook Air and I have no problem accessing the App Store from here. Do you have any other suggestions?
Open in Safari: macOS High Sierra 10.13
Thanks again. I just tried that and the download is beginning. Hopefully this will work!
You're welcome. Once El Capitan is installed you may be able to upgrade to High Sierra.
Upgrade to High Sierra Issue
