qperr.hlp (Topic list)
Important Notice
The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.
Error Message
 
Error 91:  Invalid file type
 
The file operation does not accept a file of this type.
 
Check the syntax for the file operation and make sure
the operation accepts the file type you specified. This
problem often occurs if you try to use a Text file
operation on a binary file or vice versa.