Abnormal FORMAT Termination Yields Invalid Media (84941)

The information in this article applies to:
    Microsoft MS-DOS operating system 5.0
    Microsoft MS-DOS operating system 5.0a
    Microsoft MS-DOS operating system 6.0

This article was previously published under Q84941


If you use the MS-DOS FORMAT command to reformat a fixed disk drive and you terminate the command by pressing CTRL+C (or CTRL+BREAK) at the "Proceed with Format (Y/N)?" prompt, later attempts to access the drive produce the following error, even if the drive was properly formatted before the abnormal termination:

Invalid media type reading drive X
Abort, Retry, Fail?


To regain access to the drive, do the following:

    Issue the FORMAT command again, and press N (for No) at the "Proceed with format (Y/N)?" prompt.
    Reboot the machine.


Microsoft has confirmed this to be a problem in MS-DOS versions 5.0, 5.0a, and 6.0. This problem was corrected in later versions of MS-DOS.


This condition is caused by an error in the MS-DOS FORMAT CTRL+C handler. When FORMAT is terminated at any point by pressing CTRL+C (or CTRL+BREAK), it assumes that the disk is only partially formatted and therefore unusable; therefore, the disk is marked as such.

Modification Type: Major Last Reviewed: 10/13/2003
Keywords: KB84941