Navigation services not working in WPF

Question

Hello I am working on a WPF project I am trying to stop navigating to another page without being saved to the current page for this m using navigation service.navigating event and allowing e.Cancel =true but it gives me a null exception in navigation services. How to achieve this??

Amit Gupta · Answer

As seen in the screenshot you had called the NavigationService class in the constructor of Sale page as NavigationService class may not initialized in the memory. Try this event in your Page load event. Hope this will fix this issue.

Devendra Kumar · Answer

Thank you all.. writing on page load works fine.. thanks

Devendra Kumar · Answer

Pz look at the screenshot

Afzaal Ahmad Zeeshan · Answer

Can you show me the code as well? Also it gives a null reference exception on what object or line. That would help us understand and help the problem.