Super weird issue going on. Upgraded my 13" 2011 MBP with a Samsung 840 Pro SSD to High Sierra. (Automatically upgraded to APFS with TRIM enabled) Last night it wouldn't boot showing only a flashing folder/question mark. Did all of the usual stuff PRAM, Recovery Mode, repaired permissions, etc. Nothing worked; it just won't boot.
Took the drive out of the machine and put it into a USB enclosure to see if it would boot externally and it does! I have verified that there is nothing wrong with the drive. I can boot it when it is attached to the machine externally and use it as normal. I can even make it the startup disk when external and it works flawlessly.
As SOON as I put it back into the machine, the computer says it can't find the startup disk. Has anyone ever come across this before or seen similar behavior with 3rd party SSD's??
Took the drive out of the machine and put it into a USB enclosure to see if it would boot externally and it does! I have verified that there is nothing wrong with the drive. I can boot it when it is attached to the machine externally and use it as normal. I can even make it the startup disk when external and it works flawlessly.
As SOON as I put it back into the machine, the computer says it can't find the startup disk. Has anyone ever come across this before or seen similar behavior with 3rd party SSD's??