High Sierra reboot loop after data migration I've installed a new SSD on my Mac Mini 2014. So I have a new SSD connected via PCIe and the old OEM HDD via SATA.

I've installed a fresh copy of High Sierra on the new SSD and seems to work well. But after using Migration Assistant (to copy data from HDD OS X installation to the new SSD) the system begins rebooting loop on Apple logo screen.

I've reinstalled it a few times, but the same thing happens after Migration Assistant. Any help?
Try to install High Sierra again but change the format on you SSD drive to a HFS+ and run the Migration Assistant again.

I have the same issue when I boot. I think this is because we have a Mac from early 2015. I think the Mac will not boot a drive with APFS format yet. (Maybe a firmware update will fix this).