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One of my friends who don't have a fast Internet connection asked me if I could install El Capitan (which is the highest version of OS X that his iMac supports) and I said sure.
Today I went to App Store to install El Capitan, just for it to download so that I can make a bootable USB for him, and couldn't find it in App Store.
Then after a bit of searching I've found this link and it opened in App Store:
However, when I click the get button, it redirects me to Software Update in my System Preferences and says that it's not available:
Previously, clicking Get button just downloaded an installer into my Applications folder where I could easily create a bootable USB.
How can I make bootable El Capitan installer USB in Mojave?