Win 8.1 App crashes on user device - How to debug?

last week I published my first Windows 8.1 app on the Windows Store. So far everything works fine but now two user reported that the app crashes immediately when being launched.

Additionally I discovered that there is a CrashDump listed in the Reports/Quality section of the Dashboard. I dowloaded the CrashDump and tried to find the source of the problem using WinDbg by following this instruction: http://blogs.msdn.com/b/ntdebugging/archive/2014/01/13/debugging-a-windows-8-1-store-app-crash-dump.aspx

I was able to follow the instruction almost up to the end but then the sos library is not found:

0:006> .sympath SRV*C:\Symbols*http://msdl.microsoft.com/download/symbols
... 

0:006> .exr -1
ExceptionAddress: 769eb1d7 (combase+0x000fb1d7)
ExceptionCode: c000027b
ExceptionFlags: 00000001
NumberParameters: 2
Parameter[0]: 03f3f32c
Parameter[1]: 00000001

0:006> !error c000027b 
Error code: (NTSTATUS) 0xc000027b (3221226107) - Anwendungsinterne Ausnahme. 

0:006> .ecxr 
eax=03f3f030 ebx=00000000 ecx=00000000 edx=00000000 
esi=03f3f360 edi=03f3f030 eip=769eb01f esp=03f3f314 
ebp=03f3f3bc iopl=0 nv up ei pl nz ac po nc cs=001b
ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00000212 
combase+0xfb01f: 769eb01f 6a03 push 3 

0:006> knL 
*** Stack trace for last set context - .thread/.cxr resets it
...

0:006> dt 03f3f32c combase!_STOWED_EXCEPTION_INFORMATION_HEADER*
0x05f182e4
   +0x000 Size             : 0x28
   +0x004 Signature        : 0x53453032

0:006> .formats 0x53453032
Evaluate expression:
  Hex:     53453032
  Decimal: 1397043250
  Octal:   12321230062
  Binary:  01010011 01000101 00110000 00110010
  Chars:   SE02
  Time:    Wed Apr 09 13:34:10 2014
  Float:   low 8.46917e+011 high 0
  Double:  6.90231e-315

0:006> dt -a1 03f3f32c combase!_STOWED_EXCEPTION_INFORMATION_V2*
[0] @ 03f3f32
---------------------------------------------
0x05f182e4
+0x000 Header : _STOWED_EXCEPTION_INFORMATION_HEADER
+0x008 ResultCode : 80131500 
+0x00c ExceptionForm : 0y01 
+0x00c ThreadId : 0y000000000000000000010001100101 (0x465) 
+0x010 ExceptionAddress : 0x76943bff Void 
+0x014 StackTraceWordSize : 4 
+0x018 StackTraceWords : 0xa 
+0x01c StackTrace : 0x04c6c010 Void 
+0x010 ErrorText : 0x76943bff "趍ﯰ???" +0x
+0x020 NestedExceptionType : 0x314f454c 
+0x024 NestedException : 0x05f1be44 Void 

0:006> !error 80131500 
Error code: (HRESULT) 0x80131500 (2148734208) - <Unable to get error code text>

0:006> dpS 0x04c6c010 La 7697a9f1 combase!RoOriginateLanguageException+0x3b [d:\blue_gdr\com\combase\winrt\error\error.cpp @ 1083]
63da3bc6 mscorlib_ni+0x9b3bc6
63e41976 mscorlib_ni+0xa51976
63e415c1 mscorlib_ni+0xa515c1
5b72f9df System_Runtime_WindowsRuntime_ni+0x1f9df
5b72f965 System_Runtime_WindowsRuntime_ni+0x1f965
6372de66 mscorlib_ni+0x33de66 
5b72f934 System_Runtime_WindowsRuntime_ni+0x1f934
5b6bff16 Windows_UI_ni+0x9ff16
64492a36 clr!COMToCLRDispatchHelper+0x28

0:006> !sos.pe 
The call to LoadLibrary(sos) failed, Win32 error 0n2 
"The system cannot find the file specified." 
Please check your debugger configuration and/or network access. 

0:006> .loadby sos clr 
The call to LoadLibrary(c:\symbols\clr.dll\52E0B78469b000\sos) failed, Win32 error 0n126 
"The system cannot find the file specified." 
Please check your debugger configuration and/or network access.

I does not have experience with this kind of debugging and without the instruction I would not have known any of the commands that I had to use in WinDbg.

Does anyone have an idea how to go on from here?

I have uploaded the CrashDump to my OneDrive. Would be great if anyone with more experience could have a look at it: http://1drv.ms/1gZzrRK

Is it somehow possible to get additional information from the users who reported the crash to the support? Can they extract a crash dump / error report from their systems?

Is there any possibility to supply a changed version to these users to check if these changes influence the problem?

Thank you very much!

In order to get more insight into what your app is doing when it's running on users' devices, you could add logging of some kind. Local logging to file is an option, but a poor one, since you have to let your user dig into hidden files to retreive your application log. It might be acceptable though, depending on your scenario. In that case you might want to look at this logging sample for Windows Store Apps that uses EWT to log.

Alternatives would be using some kind of logging framework. I haven't got any experience in any of those so I couldn't tell you which one to use.

As for getting a changed version to your user: simply build an app-package locally, put it on OneDrive and send them a link to it. They can sideload the app themselves (although it requires running a Powershell script and logging in with a live-account). I've used this approach with several clients and it's workable.