A ZPR message indicates that your program is about to read from the zeroth page of memoryŚread 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.
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.
On AIX, ZPR errors are suppressed by default because they are not all fatal. The AIX compiler regularly generates code that legally accesses NULL values in order to achieve cache line optimization. To display ZPR errors, set the option -ignore-zpr to no.