The not accessible fatal device hardware error (once this error occurs on a drive, that drive will become not accessible) shows up now and then on different devices (WD external hard drive and Seagate hard drive are two most common devices). Besides, you may found this error in removable drives like USB flash disk. This fatal device hardware error can also be resulted from a cable problem, hard drive/SSD physical damage, etc. The error ' The request failed due to a fatal device hardware error' usually appears when the operating system can’t access the HDD/SSD or unable to read/write files on it.
What Does Fatal Device Hardware Error Mean