A ZPR message indicates that your program is about to read from the zeroth page of memory—read from a bad pointer. An SEGV signal can result.
A ZPR error can be caused by a failure to check return status for a function expected to return a pointer to a structure or an object. If the function returns NULL on failure, accessing a structure field from the NULL pointer leads to a ZPR error.
Note:
HP-UX can be configured so that ZPR messages are not fatal. However, they still represent serious errors. A SEGV happens only if you use the -z compiler option.