Software development processes have long used Executable Assertions (EA) to manage data errors. As software tends towards more and more complicated and inter-related structures, and its pervasiveness extends towards embedded applications, the impact of errors also rises for service-critical or $-critical implications. Henceforth, it becomes of interesting to be able to model error propagation in software to aid transform ad-hoc EA placements in software into a systematic process for locating them as well as developing processes for determining EA properties for effective error containment. In this talk I will show some recent approaches and results using an error propagation analysis approach to tackle the needful. Extending beyond discrete EA placements, developing inter-EA relationships becomes useful over distributed software services and for provisioning of security.