Microsoft KB Archive/50563

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BACKUP FORMAT.COM File Not Found Problem ID Number: Q50563

4.00 MS-DOS buglist4.00


A problem occurs if the following conditions exist under MS-DOS Packaged Product Version 4.00:

  1. An environment variable contains “PATH” as the last four characters in its name (e.g. DEVPATH). If there is more than one such variable, this only applies to the first such variable in the table.
  2. The above variable is in the environment table before the PATH environment variable.
  3. The variable must not contain the directory which contains FORMAT.COM in the same format as the PATH variable.
  4. FORMAT.COM is not present in the current directory but is in a directory specified in the PATH.

BACKUP issues the following message even when it is not necessary to format a floppy disk during the backup process:

FORMAT.COM not found

BACKUP then terminates, even though FORMAT.COM is present in a subdirectory included in the PATH variable.

Microsoft has confirmed this to be a problem with Microsoft MS-DOS Version 4.00. We are researching this problem and will post new information as it becomes available.

This problem did not exist with FORMAT.COM in MS-DOS Versions 3.20, 3.21, 3.22, 3.30, or 3.30a.

More Information:

For example, this error is issued if SET produces the following output and FORMAT.COM is not in the C:directory:

COMSPEC=C:.COM PROMPT=<math display="inline">p</math>g DEVPATH=C: PATH=C:;C:;C:

The workaround to this problem is to put all of the AUTOEXEC.BAT SET commands dealing with variables ending in “PATH” after the PATH variable. This can also be accomplished by resetting the variable manually with the following command:


The following example also causes FORMAT to fail:

COMSPEC=C:.COM PROMPT=<math display="inline">p</math>g DEVPATH=C: FOOPATH=C:;C: PATH=C:;C:;C:

FORMAT fails because the “DEVPATH” variable is encountered first and FORMAT.COM is not located in the C:subdirectory or in the current directory. The example listed below works because the first instance of an offending variable “FOOPATH” is encountered. If FORMAT.COM is located in C:, BACKUP finds the FORMAT.COM file correctly.

COMSPEC=C:.COM PROMPT=<math display="inline">p</math>g FOOPATH=C:;C: DEVPATH=C: PATH=C:;C:;C: