Dec 27, 2013
Error Code 21
Error code 21 specifically known as "The device is not ready" 0x15 is an error that occurs when certain devices are having problems performing specific processing tasks. Possible causes for this problem are memory shortage, loose cables, and improperly attached devices. A solution to keep "ERROR_NOT_READY" from appearing is to reinsert the disk and retry the command.
Automatically fix Windows error code 21 now…