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I’m trying to upgrade the os on a IMac 14.1 that’s running on Nividia and I was following a video tutorial and it gave me this error. I was upgrading to Montreay so does this mean I have to upgrade to something slightly older? I was upgrading from Yosemite. I’m a little confused and if anyone could help I’d greatly appreciate it! If you can explain it like I’m 5 years old because I’m not very good at ANY of this!