Using CSM, PTF SO05907 applied with an error as the USS directory was not available - it had not been mounted.
Attempt at restoring SO05907 results in
GIM69168E ** HFSCOPY PROCESSING TO THE CC2DHFS LIBRARY FAILED FOR C2DNMI IN SYSMOD SO05907. THE RETURN CODE (12) EXCEEDED THE ALLOWABLE VALUE. DATE 18.309 - TIME 11:14:13 - SEQUENCE NUMBER 000003.
NOTE: This error can occur for any fix attempting to update a USS file.