Develop Reference

An assignment generates a System.NullReferenceException

IObjectVmFactory objectVMFactory = this.Container.Resolve<IObjectVmFactory>();
This throws a NullReferenceException.
If I do not assign the result of this.Container.Resolve to a variable, it does not throw:
this.Container.Resolve<IObjectVmFactory>().AnyMethod(...)
This has no sense to me ... someone can give me some explanation?
Extra information:
this.Container is not null for sure. Triple checked. And if it was null the second line would fail.
The class implementing IObjectVmFactory has no defined constructor so the exception is not happening inside the IObjectVmFactory implementation.
The exception has no inner exceptions and points directly to the first line.
Executing the line directly on the Inmediate Window generates a ('' is null) message.
Thanks!

My project's configuration was in Release, not Debug. In release mode, it throws an exception at the assignment. In debug, it throws on the step AFTER the assignment:
Foo member { get; }
public Bar(Foo foo)
{
// crashes here on release
member = foo;
// crashes here in debug (foo.Collection was null)
foreach (var thing in foo.Collection)
thing.DoSomething();
}
So it looks like having the project's configuration in release may cause the error. Try switching the configuration to debug and find where it's failing.
Go to Build -> Configuration Manager
Select your project
Change the configuration from Release to Debug.
Build and see if the error occurs at the same place.

visual Unhandled exception in Debugger::HandleIPCEvent when breaking on certain breakpoint

I get the following exception (in Dutch, English translation follows in the text) which breaks my debugger when I press 'OK' it stops the debug session and closes the application:
Translated in text:
---------------------------
LerTemperaturaWPF.vshost.exe - Application Error
---------------------------
INTERNAL ERROR:
Unhandled exception in Debugger::HandleIPCEvent.
Event ID=0x246.
Exception code=0xc0000005, Eip=0x68fbaeca.
Process ID=0x1094 (4244), Thread ID=0x10a4 (4260).
---------------------------
OK
---------------------------
This happens if the first time the debugger breaks are inside a certain piece of code:
private void PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
// Set value of property, only when the long editor is selected (no optionlist item is selected)
if (this.Editor.SelectedItem != null)
{
if (this.Editor.SelectedItem as OptionForList == null)
{
this.Editor.SelectedValue = ((Management.Property)this.Editor.SelectedItem).Value;
this.Editor.SelectedIndex = 0;
}
}
}
It happens when I place the breakpoint inside the 2nd if statement, before the second if statement (where ever I place it). It gives me no problems.
If I make sure the first break the debugger has is before this code and afterward it hits a breakpoint in this code there are no problems either. The debugger must have broken before getting to this code. Now I do not think it has anything to do with this code (90% certain).
The property changed is a user control and somehow I think the debugger can't handle the user control properly? maybe?
Has anyone seen this behavior before and know how to fix this? do I need to turn off (or on) some of the debug settings??

Right click on the project/solution -> Properties -> Debug -> Check "Enable native code debugging".

(1) On the Debug menu->Windows->Exceptions, and enable all Thrown check boxes. Debug the application, it will show you the actual and detailed errors in a message Box.
(2) Right click on the project/solution -> Properties -> Debug -> Uncheck "Enable visual studio hosting process".
(3) Please also change the Platform target (X86/Any CPU/X64), re-compile the app, debug it again.
(4)Tools > Options > Debugging > General > "Use Managed Compatibility Mode" checkbox.

All answers described here do not guarantee 100% cure. What I am doing as a workaround is that just stepping over to the next line while debugging.After that I can see the value of that variable in the watch on mouse hover. (In my case, stepping over to next line does not change value)

Breakpoint suddenly closes the "locals" window

I'm trying to debug a variable in my code. I'm using a break point but when my mouse goes over any of the variables present in "locals" it the locals window suddenly closes down without any warning at all. Also a lot of the lines are empty. Is this a bug?

Your watch window contains an error message "Function evaluation was aborted." That probably means one of the properties displayed has an infinite recursion, like so:
readonly bool isSigned;
public bool IsSigned { get { return IsSigned; } }
Fix the infinite recursion and the problem should go away:
readonly bool isSigned;
public bool IsSigned { get { return isSigned; } }
You can catch the StackOverflowException when it is thrown using Visual Studio by selecting from the menu bar "Debug" -> "Exceptions" -> "Find..." -> type "stackoverflow" -> check "Thrown" for System.StackOverflowException -> "OK"
If "Exceptions" does not appear in the "Debug" menu of your version of Visual Studio, follow the instructions for To add the Exceptions command to the Debug menu for your VS version.
update Just checked, looks like Visual Studio won't break on the StackOverflowException if it's thrown in the watch window. If you can't find the bug by code inspection, what you have to do to find the infinite recursion is to delete everything in the watch window, then add a line or lines in your actual code to access the properties that might be causing the recursion, checkaoprimeiroradiobuttonG in your case, e.g.
var tmp1 = checkaoprimeiroradiobuttonG;
var tmp2 = desactivabetaoadicionalG;
In that case the recursion should get caught.

How to prevent break on specific exception if it's handled

Normally I want the debugger to break on ArgumentOutOfRangeException.
But within my try catch(ArgumentOutOfRangeException) that exception is already handled and so I want the debugger to not break.
I tried the DebuggerStepThrough attribute, but it still breaks.

You can do this by setting the debugger to break on user unhandled exceptions.
Go to Debug -> Exceptions, Common Language Runtime Exceptions, de-tick (uncheck) the Thrown box. Of course you can get very precise with what you want to break on by drilling down into that list. Be aware that this setting takes effect across the whole solution, you can't set it per class or method. If you do want to be more selective per method, then consider using compile directives to not include that bit of code during debug time.
As for the DebuggerStepThrough attribute, that is to prevent breaking on break points, nothing to do with breaking on exceptions.

You should check your visual studio isn't set to break on all exceptions
On the Debug menu, click Exceptions.
In the Exceptions dialog box, select Thrown for an entire category of exceptions,
for example, Common Language Runtime Exceptions.
Microsoft Visual Studio Help

There is a way. First disable debugging code that is not yours. Go to Tools > Options > Debugging > General > select "Enable Just My Code (Managed only)". Now tell the debugger that this one function is not part of your code with DebuggerNonUserCodeAttribute:
[System.Diagnostics.DebuggerNonUserCode()]
private void FunctionThatCatchesThrownException()
{
try
{
throw new ArgumentOutOfRangeException();
}
catch (ArgumentOutOfRangeException ex)
{
//...
}
}
If an exception (some other than ArgumentOutOfRangeException) gets out of the function debugger will catch it as usual, but the location of interception will be where the function is called.

"The debugger cannot continue running the process."

I've been messing with VS 2010 debugging settings, trying to get stepping into the .NET Framework working. Well, I can't get it to work. I've also tried the Reflector VS plugin and that was working at one point.
Then I randomly started getting this error:
This only happens when I have a breakpoint on a line that calls IEnumerable<T>.ToList(). If I try to step-over or step-into on that line where my breakpoint is set, I get this error dialog and my debugging session ends.
If I move the breakpoint to the line below, the debugger makes it past the ToList() call!
I've tried the following to no avail:
Removing the Reflector plugin.
Undoing my changes in the Tools > Options > Debugging window (unchecked the option to step into the .NET Framework; unchecked the source server option; checked the just my code option).
Unchecked Microsoft Source Server in the Tools > Options > Debugging > Symbols window.
Cleared the symbol cache.
What is going on?

Because this was the first place I came to when I searched for an answer, I'll add what I found out.
In my case, I had the debugger set up in the solution to start multiple projects. For some reason this setting was changed by Visual Studio so that no project was starting. Correcting the setting in the solution immediately solved the problem.
The problem was not difficult to solve, but the error message was more than a bit irritating.

I've just found this answer useful. All I did was change my start-up project to another, and back to normal.
My project probably lost this setting somewhere, and resetting it made it available again.

It was a ToString() override that make the debugger crash ! (After the evaluation the debugger will show you the result with the ToString() method). And if you get an exception in the ToString(), you will never catch an exception because you cannot code them on the debugger behaviour.
I've got this answer from msdn

I suffered from same problem....
I found one solution which heard uncommon....
The debugger cannot continue running the process.Process was terminated
While debugging your code step by step , you will find the line , from where error redirecting.
If you are using " ToString() " anywhere in that file ,please remove that .
Instead of the ,you can use Value / Text .
It works fine.
............
If you were not used ToString() any where in program , then reload project copy by removing completely.

I had the same problem. I traced it down to a class(step-by-step debugging) and finally to a property(commenting all the code, then step-by-step uncommenting).
this property returned a typed dataSet from a table.Dataset
private typedDataSet myDataSet
{
return this.DataSet as typedDataSet;
}
this was in a DataTable partial class.
After I removed this property everything went OK.

I ran into this issue with a code bug from copy/paste. Instead of get/setting the private member variable, I did a get/set on itself. When I referenced the property in other code the debugger terminated (2010):
public bool ProdToDeve
{
get { return ProdToDeve; } // <= missing underbar
set { ProdToDeve = value; }
}
private bool _ProdToDeve = false;

This message will also show up when you're trying to debug a Xamarin solution but you have a class library selected as the startup project instead of your application porject.

It occurred to me when I was doing the following:
throw new Exception(timeout.TotalSeconds + " second(s)");
That's because timeout.TotalSeconds.ToString() which indeed is an override method for an object of type double, was throwing a Parameter not valid exception.
Finally, for safety I ended up doing the following:
throw new Exception(System.Convert.ToString(timeout.TotalSeconds));

Well, typically, this is also the kind of error message you can get in a multi-threads context. In brief, it involves concurrency : make sure that your resource accesses are always secured.
In my case, I got this error message when I forgot to secure resource accesses at some places within my code. To solve this issue, I just had to decorate the critical sections with a lock instruction (on the concerned resource). I hope this will help those who are in this context.