ASMACMS007E File 'fn ft fm' does not contain fixed length 80 character records

Explanation
The source file you specified in the ASMAHL command does not contain
fixed-length records of 80 characters.

Supplemental Information: The variable file
name, file type, and file mode in the text of the message indicate
the file that is in error.

System action
RC=32. The command cannot be processed.

Programmer response
You must reformat your file into the correct record length. CMS
XEDIT or COPYFILE can be used to reformat the file.