In this blog post, we are going to show how to use NP .NET Profiler to capture a memory dump on unhandled exception in Windows Store Applications. You can download the profiler tool from here.

Whenever a Windows Store Application gets terminated due to an unhandled exception, .NET Runtime will log an event with the exception details and complete callstack as shown below.

Click the image for a larger view

Most of the time this callstack will help us to determine the location of the unhandled exception. But in few cases, the callstack doesn’t include any application functions, so it is very hard to pinpoint the location of the unhandled exception. And sometimes only with the callstacks information, it is very hard to determine the root cause of the unhandled exception.

Memory dump just before the process termination will not only help us to determine the location of the unhandled exception but it also helps us to determine the root cause of the exception.    

Steps to capture unhandled exception dump

1. Download NP .NET Profiler tool from here
2. Extract the NPStoreApp.zip file to c:\temp\np folder
3. Double click on the NPStoreApp.exe
4. Select the Windows Store Application from the listbox
5. Set the “Profiler Type” to “Performance Profiler”
6. Set the “Filter Type” to “Namespace Based Filter”
7. Set the “Filter Settings” to “Ignore System and Microsoft Namespaces”
8. In the “Profiler Options” enable the “Capture Unhandled Exception Dump” as shown below

   

9. Click on the “Start Profiling” button. This will launch the application and the profiler will now monitor for unhandled exceptions.
10. Reproduce the unhandled exception
11. As soon as the unhandled exception is raised, the application gets terminated and just before termination, profiler captures a full memory dump
12. The memory dump file is saved to the temp folder. Just click on the “Open Output Folder” button to view the dump file location as shown below

    Click the image for a larger view

    

13.   Now open this memory dump file in WinDBG and execute following commands
1. !symfix c:\websymbols
2. .loadby sos clr
3. !clrstack
4. !dso
5. !pe <exception object>
14. Here is the WinDBG output for these above commands
1. !clrstack shows the exact callstack as captured in the eventlog
2. !dso provides the address of the exception object that was not handled
3. !pe provides the exception details and the callstack that raised the exception
1. The location of the handled exception is  : TestApp!TestApp.MainPage+<CrashTest>
2. The root cause of the exception is  : calling UI element from a worker thread