Xamarin + Visual Studio 2017 on Android: how debug Exception? - debugging

I have taken over a Xamarin.Forms (C#) application from an external source for fixing.
Problem is, that the application does sometimes fail with a runtime error:
System.NullReferenceException: Object reference not set to an instance of an object
The message appears in the output console and in a separate message window in Visual Studio. Unfortunately neither gives any more information about the failed object, a source code line number or a classname, there is just the bare message. Furthermore the "Call Stack" window in Visual Studio is always empty --> I have no easy way to find out where the failure occurs in foreign source code, because virtually no documentation of the program flow exists.
Full source code is available, and I have re-built the application with "Debug" configuration.
Right now the only option I can think of is to scatter breakpoints and Debug.Writelines all over the source code to get an idea where the problem occurs.
Is this really my only option, or did I miss some setting somewhere, so I can retrieve more info, so I can somehow go straight to the code where the failure occurs?
Thx!

Related

Why does a generic UWP app show an error?

I created a simple UWP app from the VS 2017 blank UWP template. No added XAML or C# code-behind:
Create new app with Blank Universal Windows template
Set Debugger type to Mixed (Managed and Native)
Build and Run (No XAML or code added)
Following error: WinRT originate error - 0x80070490 : 'Element not found.'
This happens every time. Does anyone have a handle on this error? If I don't have Mixed Mode debugging on, I don't see the error but I'm assuming it's still there. Is this an error that I should be concerned about?
Thank you.
A lot of problem may result this error, and it should not be a fatal error in your case. Most likely you changed the default Exception Settings in visual studio.
Just like all other apps, Windows use exceptions and catch them at different level.
For end user, you should not see this exception and app should not crash.
In your situation, I think you click continue and the program should not crash, and it should not be a big concern.
I suggest you:
1, start and debug your app, open Debug|Windows|Exception Setting, then click the 'restore the list to default settings' button
2, restart your app.
3, You should not catch the exception, but you still see error message in Output window.
If you still see a exception window popup, you need to post more information like your os version, and then someone can help you
I met this error when I call the winRT api CommunityToolkit.WinUI.Notifications.ToastNotificationHistoryCompat.Clear(). Then let the app toast someting once the error had gone.

Visual studio form editor error

I have an error in my form editor preventing me from modifying the form.
I know in which control this occurs but no way to find what exactly causes the problem.
I tried setting breakpoints in the InitializeComponents() of the form I try to open but it doesn't stop (I am in debug mode...). I also tried to attach using a second instant of Visual Studio as demonstrated here, but even when setting all debug exception options to "throw", the attached process doesn't stop and indicate anything about call stack nor other useful information...
All I know is that there is a disposed object I'm trying to access, but absolutely no information as to where in code, etc..
What could I possibly do to debug the situation - knowing which control is the cause but absolutely no idea as to which of the 300 lines of code causes the issue...

Visual Studio 2013 crashes consistently when typing in an object/collection initiazlier?

Has anyone else ever seen this happen? I've had Visual Studio crash over and over again when typing in an object initializer: https://msdn.microsoft.com/en-us/library/bb384062.aspx
I suspect it's some kind of Intellisense bug, since it seems to occur only when the space or period key is pressed. I'm really curious what's triggering the sudden and reproducible crash and if there's any patches or workaround to prevent it from occurring.
The image shows where the cursor is when typing within the first set of brackets. This code appears in a method, which implements an interface member for the class.
This appears to have been caused by the "HideShow Comments" extension. I'm still not sure why it occurs, but disabling the plugin stops the crash from occurring and re-enabling the extension causes the crash to occur again. This must be a problem with Visual Studio itself, since it's the only common denominator in all these extension-related crashes.
I attached a debugger and caught the following error:
An unhandled exception of type 'System.NullReferenceException'
occurred in HideShow.Implementation. Additional information: Object
reference not set to an instance of an object.

Unable to determine application identity call? How to track down?

I am making a windows phone 8 application and in the designer view in both blend and VS I get "Unable to determine application identity call" error as a dialog box.
From what I read on stack this is propably because of the Isolated Storage is getting run and the designer can't handle it.
I am wondering is there away I can get some line numbers or something where the errors are happening instead of having to manually go through the code?
By the time you see this message box it is already too late, the exception was caught and handled. You have to catch it when the exception is raised. Which is not so easy to do at design time.
One technique that's worth a shot is to use a debugger to debug Visual Studio itself. Start it again and use Tools + Attach to Process. Locate the first devenv.exe in the list of processes and select it. Set the Attach to: setting to "Managed (v4.5, v4.0)" and click OK. Let it trundle to find the PDBs (takes a while). Debug + Exceptions, tick the Thrown checkbox for CLR exceptions.
Switch back to the original instance of VS and do whatever you did before to trigger the error. The 2nd instance will break in when the exception is thrown. Which some luck you'll see your code on the Call Stack window. If the debugger doesn't break then repeat the exercise but attach to XDesProc.exe, the XAML designer. Good luck with it.
Isn't this
Unable to determine application identity of the caller?
or
Getting Unable to determine application identity of the caller Error
are the same topic????
Don't know, just asking...
Sorry for any inconvenience..
Just answered in my basic question.
I'm afraid, i don't know how to get exact string number, just keep in mind that Designer cant have an access to the IsolatedStorage and check all places where you're working with IsolatedStorage. Basically, what you need to do is to add to all constructors a lines
if (ViewModelBase.IsInDesignModeStatic)
return;
If you're working with MVVM Light, or
if (System.ComponentModel.DesignerProperties.IsInDesignTool)
return;
which is pretty the same but without MVVM Light.
Also, i edited my answer there.

Error HRESULT E_FAIL has been returned from a call to a COM component

In Silverlight 4 app; what does this error mean?:
"Error HRESULT E_FAIL has been returned from a call to a COM component."
It's a very generic error. The VS debugger doesn't point to the exact location of the error when debugging.
This is kind of an old question, but I figured I'd give my answer since I found this thread by Googling for the exact same problem.
In my case, I'd copied some sample XAML from the web to get started with Silverlight Toolkit 4. That sample XAML contained a simple button with a click event handler that didn't relate to any handler that actually existed in my code behind. I didn't notice this simple problem at first, because the compiler didn't give me an error message, I just saw the "Error HRESULT E_FAIL has been returned from a call to a COM component" message above at runtime. It was only when I isolated my sample XAML by copying it into a brand new Silverlight application without any other content that the real underlying problem was revealed at compile-time.
So, if you've got the same error message at runtime, my advice is to check your XAML carefully for any errors that you had expected should have been picked up at compile time, but which for some reason ended up as the runtime error noted above. In order to debug, you can do what I did and isolate the code that's causing the error in a standalone Silverlight app with no other content, and see if like me you get a more helpful error message to guide you.
HTH.
There are many solutions out there but this is the only solution that worked several times for me.It has been tried on VS2012 VS2013 and VS2015, I find it working equally good for all.Just follow steps bellow to fix this issue
Step 1 : Close Visual Studio
Step 2 : Delete *.csproj.user and *.suo files
Step 3 : Reopen VS, and try to run project again in debug mode.
NOTE : This situation occurs when multiple users working on same
project with different VS versions .suo file is not supported
for round-tripping between the two VS versions.It contains information
about what settings current user has selected for his/hers VS working
environment.
In my situation:
I create a
class MyControl : ContentControl {
}
By default, the class is not public and XAML cannot load it and throw exception
Error HRESULT E_FAIL has been returned from a call to a COM component
Just change the scope of class to public and error disappear.
Hope this help.
PS. Microsoft should provide more on information than just throw a mystery error message without any stack trace.
I also had this error and I found that this problem is related to not have added all requiered assemblies to your project. In my case I was using a UserControl with a depency with the Silverlight Toolkit and I havent added this reference.
I just added the reference and everything solved :)
I had this error using the current SL4 Telerik controls. A similar issue has been reported here with a solution ... of sorts. The problem seems to be with the way Expression Blend manages the cache of controls.
Here's one way to generate this error, which I stumbled upon today. We have the following button in XAML:
<Button x:Name="button" Click="Button_Click" Content="Click me" />
The event handler that handles the button's Click event is as follows:
private void Button_Click(object sender, RoutedEventArgs e)
{
button.Margin = new Thickness(0, double.NaN, 0, 0);
}
When I click on the button I get the aforementioned error. The same error arises if I replace NaN with PositiveInfinity or NegativeInfinity.
Interestingly, I get a different error message if the first parameter of the Thickness constructor contains the NaN instead of the second.
I had this error from problems with XAML. The strange thing was that I had missing resources used by Style and Margin attributes - which means the app runs fine, and even resharper only reports a 'hint'.
Once I cleared up those problems my "Error HRESULT E_FAIL has been returned from a call to a COM component." disappeared. As others have said though, this is a vague error, very difficult to debug. In this case I have inherited a large project with 100's of VS and ReSharper messages with varying severity - missing StaticResource on Style attributes were not the first place I checked!
I had this error in my xaml page and there were no syntax errors. Cleaning and re-building the project solved my issue. fyi...
The IIS App Pool has to run as an account that has query access to the Team Foundation Server. This fixes the problem for me.
Most of the reason of this problem related dependency propertied on component design.
You just face off this problem on design.
Soulution is easy but takes time :) Clean project and rebuild all. When you enter the desing again you should see everything is fine!
I hope this helps!
If you see this exception recently, please try to re-install silverlight sdk4.
This is a security and permissions issue. Look into the IIS and make sure Integrated Security is ON. Then set Application Protection level to Medium (If it is high then this might be the result). Then check your Web.Config file. Make sure impersonation is off.
This should help.
I had this problem while I was encoding Live video and audio (using Microsoft Expression) and the next piece of code throws the exception randomly:
// Set bitrate
liveJob.OutputFormat.VideoProfile.Bitrate = new ConstantBitrate(2500);
// Set Video size
liveJob.OutputFormat.VideoProfile.Size = new Size(320,240);
until i've figured out that the second line throws the exception while the first one is still running in another thread !
and of course, it was my fault - i've called the method in code, and it was also been called by Click event...
I had this exception and went nuts. I would advice you check if you had recently installed a component that had possible conflicting namespace items. In my case I installed the windows phone tool-kit which had items that were similarly named with the stock tool kit on windows phone.
Asap I uninstalled this from the Nuget package manager, all was back to normal.
Here is what FINALLY fixed this problem for us when trying to use MICROSOFT.TEAMFOUNDATION library when querying Team Foundation Server:
Team Foundation Explorer has to be installed with the currect version that is referenced in the application.
MSDTC – Configuration. (See DTC config below)
IIS App Pool has to run as an account that has query access to the Team Foundation Server
IIS App Pool has to run as an account that has COM access on IIS Server (We have a dedicated server for this so we made the identity user an administer on the local server).
Firewall has to be off or configured to allow COM access for DTC service.
DTC config ----
Click Start, click Run, type dcomcnfg and then click OK to open Component Services.
In the console tree, click to expand Component Services, click to expand Computers, click to expand My Computer, and click to expand Distributed Transaction Coordinator.
Right click Local DTC, and click Properties to display the Local DTC Properties dialog box.
Click the Security tab.
In the Security Settings section, click Network DTC Access.
In the Client and Administration section, select Allow Remote Clients and Allow Remote Administration.
In the Transaction Manager Communication section, select Allow Inbound and Allow Outbound.
In the Transaction Manager Communication section, select Mutual Authentication Required (if all remote machines are running Windows Server 2003 SP1 or Windows XP SP2 or higher), select Incoming Caller Authentication Required (if running MSDTC in a cluster), or select No Authentication Required if some of the remote machines are pre-Windows Server 2003 SP1 or pre-Windows XP SP2. No Authentication Required is the recommended selection.
I hope this helps.
My problem was a missing Style. I had overridden a control template with a custom brush like so:
<Style x:Key="MyCustomStyle" TargetType="Thumb">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Thumb">
....
<TextBlock Foreground="{StaticResource MyCustomBrush}"
and was missing my definition of MyCustomBrush, like so:
<SolidColorBrush x:Key="MyCustomBrush" Color="#FFAC0909"/>
and then BOOM, app didn't startup and I got that COM error message.
Well, I was almost going to eat my computer..
At last, I find out the problem is that I MAYBE BY ACCIDENT removed one parameter of one Margin setting of an Image object in the XAML page, orz..
Margin="0,-20,0"
which should be
Margin="0,-20,0,0"
Obviously I didn't realized I have ever modified anything of the XAML, so I have been troubleshooting the code behind for "a little while"..
Fortunately, I found this post and rechecked everything include the XAML page.. that was ... something...
For me, I narrowed it down to a SplitButton control that I downloaded off CodePlex ages ago. I had upgraded the solution from Silverlight 4 to Silverlight 5 and got slammed with this error. I was able to narrow it down by commenting out the XAML to all controls then uncommented it back in one by one until the error appreared again:
System.Reflection.TargetInvocationException was unhandled by user code
Message=Exception has been thrown by the target of an invocation.
StackTrace:
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Delegate.DynamicInvokeImpl(Object[] args)
at System.Delegate.DynamicInvoke(Object[] args)
at Homexaml_3.BindingOperation(Object BindingState, Int32 , Action )
InnerException:
Message=Error HRESULT E_FAIL has been returned from a call to a COM component.
StackTrace:
at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
at MS.Internal.XcpImports.UIElement_Measure(UIElement element, Size availableSize)
at System.Windows.UIElement.Measure(Size availableSize)
What fixed it was manually removing the outdated references System.Windows.Control and System.Windows.Controls.Toolkit then re-added them from the Silverlight 5 SDK folder.
Hope it helps someone (and helps me!) if it happens again a few months down the road.
I received this error recently in VS 2013 for a Silverlight 5 project. None of the above worked for me. Oddly enough, it was a threading problem (normally I am used to an exception that explains this if I am trying to create UIElements on a background thread by mistake).
Wrapping my code that adds UIElements to the MainPage with Dispatcher.BeginInvoke solved the problem:
Dispatcher.BeginInvoke(() =>
{
// your code
});
Most of the times its difficult to see where exactly the problem is located especially in XAML.
Another way to find out where its failing is to perform the following steps
Copy the exception it shows in the output window of Visual Studio. example. System.Reflection.TargetInvocationException
Click on Debug -> Exceptions. It shows up the exception list.
Click on the "Add.." button.
Paste the exception copied in the step 1 in the text box. Select "Common Language Runtime exceptions" in the drop down list.
Click on "Ok" button. The selected exception will be highlighted. Make sure you check the checkbox against the exception. Click on "Ok" button again to close the dialog.
Now run the application in debug mode. The application breaks when the exception occurs. Sometimes in the assembler mode as well.
At this point in time you have two options,
Click on the View details of the exception screen shown. Dig into
the inner exceptions until you get a clue from where its
originating.
View the call stack to see which code of line of your is causing
this exception. This will provide clues to resolve the issue.
For me, this was a XAML parsing error. In a data template, I had an extra S between two tags (probably because I pressed S instead of CTRL+S). For example...
<DataTemplate>
<Border/>s
</DataTemplate>
So, I would suggest you look for poorly formatted XML in the view that causes this exception when displayed.
In my case it was, when I tried to import database into the SSDT project, but this database already was in project, but was empty. I've just updated my project with Tools -> SQL server -> New schema comparsion. Source - database, target - project. Compare - update.
Hope it helps to someone
This error seems to be a 'catch-all' for errors that otherwise are not given a specific definition or tracing, especially those having to do with relatively external Xaml code.
In my particular case, there seemed to be an issue with the namespaces. My UserControl is in its own namespace (creatively named "UserControls"). My Pages are in their own namespace ("Pages"). I wanted to reference an enum definition in the Pages namespace from within my UserControl, so I simply added a using statement: using MySolution.Pages;. Trivial enough, and I didn't want to believe that this was the problem. But when I removed that using statement and simply created the enum in my UserControls namespace, voila, no more HRESULT error and also, as an added bonus, my dependency properties defined in the UserControl, which otherwise were mysteriously not showing up in the Xaml intellisense, suddenly were there and ready to use.
I suspect that underlying cause for this in my case was some sort of circular reference issue. And since there was no more specific error available to relate that information to me, it simply got shuffled into this HRESULT E_FAIL Com error.
I fixed this error by deleting the XAML file and add a new one from add new item. Then I pasted the XAML codes that was there in the old file.
This is an old question but in my case, none of the above solutions worked. I was trying to update the NuGet packages in Visual Studio 2017 but I was getting the following Exception.
update-package : Failed to add reference to 'System.Web.Razor'.
Error HRESULT E_FAIL has been returned from a call to a COM component.
In fact, other NuGet commands like restore-package were failing with similar exception message.
I discovered a few assemblies were missing under the packages directory so I deleted the packages directory and returned back to the Visual Studio 2017. When I opened the solution it asked me to restore the packages and after that, I was able to update the packages.
NOTE: Take a backup of package directory before deleting it.
I encountered this same error after installing VS2019 and trying to open a large solution (20+ projects), with both vcxproj and csproj projects, that target VS2015. The csproj all loaded fine, while the vcxproj all failed with the OP's error. Deleting the .vs folder did not work.
What did work was setting VC++'s "Fallback Location", under the "Browsing Database Fallback" settings.
Tools (menu)
-Options...
--Text Editor
---C/C++
---Advanced
----Browsing Database Fallback
-----Fallback Location
I set mine to D:\VC++\v16. Where I use v140 for VS2015 and v141 for VS2017. Also set "Always Use" and "Do not warn".
If anyone facing this issue, while adding reference in console/windows applications, follow the below steps
Open "Developer Command Prompt for VS 2017" as Admin
CD into "C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\PublicAssemblies"
Run "gacutil -i Microsoft.VisualStudio.Shell.Interop.11.0.dll"
Restart Visualstudio
Reference - https://developercommunity.visualstudio.com/t/add-a-reference-raise-error-error-hresult-e-fail-h/260196

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