This forum post is simply to inform you all of the process it took me to get High Sierra installed on my mid 2012 MBP.
So back in August of 2017 I bought a 2010 MacBook. Not a pro it was the all white one. And recently it had started to become slow. To the point where I could barely use it. So I purchased a 2012 MBP on eBay. When I got it it was factory reset and had Mojave already installed. The problem with that is that the hard drive it was installed on was an older hard drive. My boot time neared 6 mins. I thought maybe either Mojave had something to do with it along with the age of the hard drive that was installed. So I decided to take the SSD out of my windows laptop. Format it and install High Sierra to it. So i creates a bootable high Sierra installer from my old white unibody MacBook and went to go install it on the MBP that I had already installed the SSD into using one of those hard drive caddy’s that replaces your dvd drive. So I loaded up the installer and it started to install. Then with 2 mins left my MBP shuts off and restarts saying my MacBook restarted because of a problem. So I tried a few more times with the same results. Nothing I can do seemed to work. So eventually what I ended up doing was hooking the SSD up to my old MacBook unibody using a SATA to USB Cable. Ran the installer on that MacBook and it installed within 30 mins and was good to go. Put the SSD back into my MBP and it starts right up. Boot time was down to 20 seconds and everything worked like a charm. Don’t know why the MBP would not let me install high Sierra while the SSD was hooked to it but after all the troubleshooting and confusion I got everything up and running and have had no issues. So moral of the story is. If you’re going to replace the hard drive in a MBP you might want to consider installing the os on a completely different MacBook if you can. It will save you the headaches I had to deal with.
So back in August of 2017 I bought a 2010 MacBook. Not a pro it was the all white one. And recently it had started to become slow. To the point where I could barely use it. So I purchased a 2012 MBP on eBay. When I got it it was factory reset and had Mojave already installed. The problem with that is that the hard drive it was installed on was an older hard drive. My boot time neared 6 mins. I thought maybe either Mojave had something to do with it along with the age of the hard drive that was installed. So I decided to take the SSD out of my windows laptop. Format it and install High Sierra to it. So i creates a bootable high Sierra installer from my old white unibody MacBook and went to go install it on the MBP that I had already installed the SSD into using one of those hard drive caddy’s that replaces your dvd drive. So I loaded up the installer and it started to install. Then with 2 mins left my MBP shuts off and restarts saying my MacBook restarted because of a problem. So I tried a few more times with the same results. Nothing I can do seemed to work. So eventually what I ended up doing was hooking the SSD up to my old MacBook unibody using a SATA to USB Cable. Ran the installer on that MacBook and it installed within 30 mins and was good to go. Put the SSD back into my MBP and it starts right up. Boot time was down to 20 seconds and everything worked like a charm. Don’t know why the MBP would not let me install high Sierra while the SSD was hooked to it but after all the troubleshooting and confusion I got everything up and running and have had no issues. So moral of the story is. If you’re going to replace the hard drive in a MBP you might want to consider installing the os on a completely different MacBook if you can. It will save you the headaches I had to deal with.