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System.NullReferenceException from Xamarin iOS Debug Chain RRS feed

  • Question

  • User65001 posted

    I am on the latest Xamarin Update (4.0.1.93). As of starting yesterday I get the following hickup, when debugging iOS from Visual Studio:

    Object reference not set to an instance of an object. System.NullReferenceException: Object reference not set to an instance of an object. at Xamarin.VisualStudio.Debugger.AD7DebugExceptionEvent..ctor(Thread thread, String description) in C:\Users\builder\data\lanes\2853\c7ebc0f3\source\XamarinVS\src\Core\VisualStudio\Debugging\MonoTools.Engine\AD7Events.cs:line 433 at Xamarin.VisualStudio.Debugger.ExceptionsAdapter.OnExceptionThrown(Object sender, TargetEventArgs args) in C:\Users\builder\data\lanes\2853\c7ebc0f3\source\XamarinVS\src\Core\VisualStudio\Debugging\MonoTools.Engine\ExceptionsAdapter.cs:line 42 at Mono.Debugging.Client.DebuggerSession.OnTargetEvent(TargetEventArgs args) at Mono.Debugging.Soft.SoftDebuggerSession.HandleBreakEventSet(Event[] es, Boolean dequeuing) at Mono.Debugging.Soft.SoftDebuggerSession.HandleEventSet(EventSet es) at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler()

    Any ideas?

    Kind regards!

    Thursday, February 4, 2016 8:55 AM

All replies

  • User188911 posted

    Same here, just updated to Xamarin Forms 2.0.1.6505 and Xamarin Studio to 5.10.2

    Friday, February 5, 2016 6:49 AM
  • User2035 posted

    I'm getting the same error running against Android using 4.0.1.93.

    If I change to the MS Debugger I can deploy to the device and the app runs 100% (obv with no debugging).

    So it is definitely a Xamarin Debugger issue.

    Sunday, February 7, 2016 4:50 PM
  • User72049 posted

    I have the same issue with Android debugging. My app is running smoothly in release mode but not in debug mode

    Object reference not set to an instance of an object. System.NullReferenceException: Object reference not set to an instance of an object. at Xamarin.VisualStudio.Debugger.AD7DebugExceptionEvent..ctor(Thread thread, String description) in C:\Users\builder\data\lanes\2853\c7ebc0f3\source\XamarinVS\src\Core\VisualStudio\Debugging\MonoTools.Engine\AD7Events.cs:line 433 at Xamarin.VisualStudio.Debugger.ExceptionsAdapter.OnUnhandledException(Object sender, TargetEventArgs args) in C:\Users\builder\data\lanes\2853\c7ebc0f3\source\XamarinVS\src\Core\VisualStudio\Debugging\MonoTools.Engine\ExceptionsAdapter.cs:line 67 at Mono.Debugging.Client.DebuggerSession.OnTargetEvent(TargetEventArgs args) at Mono.Debugging.Soft.SoftDebuggerSession.HandleBreakEventSet(Event[] es, Boolean dequeuing) at Mono.Debugging.Soft.SoftDebuggerSession.HandleEventSet(EventSet es) at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler()

    Some one please give me suggestion Thanks

    Monday, February 8, 2016 7:09 AM
  • User65001 posted

    This is also quite simple to reproduce. Just start an App in Debug/Simulator (iOS), let it run for 15min without any interacting and the exception will apear. The App is then no more responsive.

    Monday, February 8, 2016 8:34 AM
  • User136063 posted

    Same here. I'm having to resort to copious log statements.

    Friday, February 12, 2016 11:32 PM
  • User191128 posted

    Android xUnit test runner crashing for me in debug mode.

    Monday, February 22, 2016 9:42 PM
  • User103661 posted

    I'm still using Xamarin.VisualStudio v4.0.0.1717 because it doesn't have this issue. All versions I've tried after 1717 have the debugging issue.

    Tuesday, February 23, 2016 4:49 PM
  • User65001 posted

    Xamarin come on - any heads up?

    Tuesday, February 23, 2016 4:51 PM
  • User139298 posted

    The heck is with this issue? I seem to have hit a critical roadblock with it. I can't figure out what it means or any way around it. The stacktrace definitely makes it seem like something is up on Xamarin's side. Come on Xamarin, don't ignore this.

    Thursday, March 3, 2016 7:26 PM
  • User103661 posted

    The issue still exists for Android with the recently released Xamarin 4.0.1.145 and Xamarin.Android 6.0.2.1. Looks like I'll be downgrading to 4.0.0.1717 again, which is the last build to not crash randomly while debugging.

    Tuesday, March 8, 2016 5:16 PM
  • User13824 posted

    I will tentatively close this forum thread to direct further discussion and updates onto a corresponding public bug report that now includes a candidate fix for this issue: Bug 39433.

    One small caution is that the candidate fix has so far only been tested on Xamarin.Android. The fix is in a debugging library that is shared by both platforms, so in theory it should help with the problem on both Xamarin.Android and Xamarin.iOS. If anyone continues to see the issue only on Xamarin.iOS after updating to use the candidate fix, the best way forward will be to submit a zipped up test case that demonstrates the problem. You can submit that test case either via a new bug report or via an email to "Business & Enterprise Support". Thanks in advance!


    (As always, I'm also happy to reopen the thread upon request within the next month or two. Just send a quick email to contact@xamarin.com with a link to this thread. For follow-up after the next couple of months, if the remaining related open bug reports or forum threads do not cover the desired scenario, please follow the recommendations to create a new bug report, forum thread, or Stack Overflow question. Thanks!)


    Special thanks also to MarkusSchiller for getting in touch via a "Business & Enterprise Support" email to get this issue into the bug tracking system.

    Since the forums themselves are not currently set up to handle bug reports, it is important to file a new bug report or contact the Xamarin support team by "Business & Enterprise Support" any time you hit an unexpected behavior in the product that you suspect will need to be debugged and resolved by the Xamarin engineering team. Thanks as always!


    EDIT: Fix typo.

    Tuesday, March 8, 2016 6:52 PM