How can I download High Sierra?
MacOS High Sierra seems to be no longer available in the App Store
Can I still get it for my iMac 2011 running Sierra?
iMac 21.5″, macOS 10.12
The links from Apple to older macOS versions is not working as of yesterday.
When they fix the links, it will work again. We do not know how long it will take to fix.
Here is the page of older macOS versions: https://support.apple.com/en-us/HT211683