Debugging XC130003 FDCs with MQS_ACTION_ON_EXCEPTION - Middleware News Problem(Abstract) You have an application that fails with an FDC from the xehExceptionHandler component, this happens because it received a signal like SIGBUS or SIGSEGV. You want to know how to find the cause of the failure with the MQS_ACTION_ON_EXCEPTION environment variable. Cause The MQ xehExceptionHandler function catches synchronous terminating signals such as SIGBUS (bus error), SIGSEGV (segmentation fault), SIGILL (illegal instruction) and SIGFPE (floating point error). These signals indicate a serious fault, such as dereferencing a NULL pointer, which needs to be investigated by the program developer. Resolving the problem The WebSphere MQ Application Programming Guide describes how WebSphere MQ handles signals on UNIX systems. The MQS_ACTION_ON_EXCEPTION environment variable controls what the MQ signal handler will do when it is called. MQS_ACTION_ON_EXCEPTION must be assigned one of the follow