An attempt to open data set dddd failed. cc is the return code in register 15 and nn is the value of the feedback field in the Access Method Control Block (ACB).
Batch backout processing stops.
For an explanation of the codes in this message, see z/OS® DFSMS Macro Instructions for Data Sets for macro OPEN. Look at the codes and correct any errors, then resubmit the batch backout job. If you are unable to correct the error, contact your local IBM® Support Center.