Error received on the following step:
Save and Upgrade Model and Object Libraries SBMJOB CMD(YAPYMDLCHG MDLLIB(PCR1MDL)) LOG(4 00 *SECLVL) LOGCLPGM(*YES)
Pressing enter Receives Y2E0028 error message:
Message:
Previous conversion of Model PCR1MDL not completed
CAUSE: A previous execution of YAPYMDLCHG for model PCR1MDL failed to complete, so model contains work files whose names begin with 'Z'.
RECOVERY:
(1) Determine cause of failure and correct error. Consult customer support if uncertain.
(2) Restore model from a backup and re-run YAPYMDLCHG command. 

Corrupted models

IBM ISERIES

Y2E0028 error code.
This is resolved by deleting the old ZJOBLSTRFP file and then rerunning the YAPYMDLCHG command.