Chosen Solution
Sadly the M.2 blade SSD won’t work in your system. Between the adapter and SSD when moving large amounts of data the data and control flow data becomes corrupt. Nothing you can do here other than replace things. You really need to get either a real Apple blade SSD or get one that is designed from the ground up to meet the Apple I/O interface. These adapter solutions just don’t hold up. Here’s what I would get: iMac Intel 21.5" (Late 2013-Mid 2014, Select Models) Blade SSD Upgrade Bundle or a real Apple unit Custom Apple 1TB PCIe 2.0 four-channel interface SSD I’ve taken out so many its not funny!
