COBRT161 Illegal intermediate code (Fatal)

The intermediate code which is currently being processed is not valid code. You are probably trying to execute a corrupted file or one which has not been submitted to your COBOL system successfully.

Resolution:

You should resubmit your source program to your COBOL system, to try to obtain uncorrupted intermediate code.

or:

If your application is invoking the File Handler directly using calls to EXTFH or mFFH, you might encounter this error if the key definition block has been incorrectly defined. Please refer to the File Handler reference documentation for details about the correct format of the key definition block.