I have an WPF app, all seems to run fine with one exception - the designer rarely, if ever, loads correctly. Usually complaining about Undefined CLR namespace. and then saying it can't find a few of my local: defined controls.
Is this just a defect in the designer or Visual Studios code generation or actually systemic of something wrong with my application?
In your code can be an error which occurs only in design time. It is possible to debug it. See How to: Debug a Designer Load Failure. Shortly you need another instance of Visual Studio and attach it to the one displaying your wpf app. You can even try to follow the error to its roots with How to: Debug .NET Framework Source.
I had a similar problem and I successfully tracked it down to DataContextChanged event handler and got rid of it.
Related
I have no clue how long this feature/option has been around but my mouse happened to pause over this button within the WPF designer early and now I'm curious what it's purpose is.
Hovering over the button, Visual Studio pops up a tooltip that says Enable project code. When I click on it, the designer seems to reload the xaml contents but I can't tell what's changed.
What does this feature do?
2020 EDIT
It's been years since I've had to work in XAML, but I've received a new project where I need to work in XAML. This feature/button seems to have disappeared. Where has it migrated?
What does this feature do?
It enables or prevents the designer from running your code in the background.
Disabling project code can lead to a loss of design time data and enabling it can lead to unhandled exceptions in the XAML designer.
These exceptions are usually caused by code that attempts to access properties or methods which work differently when your application is running in the designer compared to when it runs as a built executable.
Debugging or Disabling Project Code in XAML Designer: https://msdn.microsoft.com/en-us/library/mt622752.aspx?f=255&MSPPError=-2147217396
My application is working fine, all of a sudden while loading a designer in wpf form, im getting errors.
Object reference not set to instance of an object.
As if it is in a loop. After pressing the enter button for sometime. Im getting this error.
Microsoft Visual Studio XAML UI Designer has stopped working.
And after this, im getting this.
System.Runtime.Remoting.RemotingException
[9980] Designer process terminated unexpectedly!
The number in square brackets is changing evrytime.
Im using Visual Studio 2012. Im not yet running the application, Im just switching to designer mode from code behind. If I compile and run the application, it runs fine.
Kindly help.
Edit:
Here are the three errors in single image. (I cant post morethan one link)
xamlerrors
There's an error either in the code-behind or DataContext (if you're using a ViewModel). After you fix that error, click on Click here to reload the designer. What's happening is that the designer is trying to load everything up during design time and since there's an error, it's unable to, as if the program was actually running. That null reference exception can be a bit misleading in terms of trying to figure out the cause, because it'll be thrown if you have an error in your code-behind or ViewModel.
Things to check:
Is your View referencing the correct ViewModel?
Is your code-behind portion of the View matching the View name? Some people copy their Views, but forget to change the Class name in the code-behind.
Do you have any errors in your ViewModel?
What about models? If they're loaded during design time and contain errors, this could cause the above exception.
I noticed that those kind of errors are almost everytime caused by
an error in the parameterless constructor of the view
an error in the constructor of the view model which is attached to the view
Keep in mind that when the designer loads, it calls the parameterless constructor of the view (there has to be one for the designer!). If there are "complex things" done there which can only performed correctly at runtime, there will likely be errors at design time.
The same is true for the constructor of the view model which is called from the view.
Check whether design mode is active
For example you should not load data from a repository in a constructor.
If you do it in the constructor, at least check whether the design mode is active or not like explained in this answer here about the GetIsInDesignMode attached property and only do the complex logic in the constructor if the design mode is not active.
Debugging the problem
You also have the possiblity to debug the problem. In order to do this, you have to open a second instance of Visual Studio and debug the designer process of your original Visual Studio instance from there.
The process is described in detail here: Debugging an Exception (only) occurring in design view
I have a WPF application which is giving me a very very annoying error
System.Runtime.Remoting.RemotingException
[12068] Designer process terminated unexpectedly!
The number between [] changes each time
The XAML is very simple
<UserControl x:Class="STC.Reports.ReportGenerator.Views.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
</UserControl>
This has wasted me hours and hours
Does anyone know anything that could help?
I cant get any more information than that above
Even though I have told VS to break on these Exceptions it doesnt
I have also tried to attach another VS and that makes no difference
I have repaired my installation of VS (2012 Professional)
I have also updated to Update 3
This is even happening when I create a brand new WPF application
Everything seems fine initially, then VS just hangs and the remoting error occurs
Paul
What kind of message are You getting?
If it is a Messagebox when You try to use designer - it is a known issue since VS2010 as far as I remember. It is frequently caused by a video card or its driver, so the easiest way is trying to update your video driver or use some older version. Sometimes that help.
The other way is not to use built-in designer. As for me, I wite pure xaml and it seems to be more convenient and faster way of development. Or, if You like visual UI - You may use Blend. AFAIK it is a part of VS2012 now.
I had this error occur for all windows/controls in a project, even if they were brand new empty windows. I had a markup extension causing a design-time exception (with no indication of this from Visual Studio) and I would get this designer error if I used the markup extension in any project resource dictionaries.
Old post but might be useful for future developers who run into this kind of problem.
I had this exact behaviour. Turned out to be a problem related to my viewmodel. At runtime everything works, but at design time VS will try to load the viewmodel standalone and things got haywire. My viewmodel depended on some global object which I created elsewhere at application startup. Loading the viewmodel standalone creates a exception since the global object was missing.
Quite easy to detect actualy. Just test your viewmodel by instantiating it yourself from code. If it fails VS won't be able to run the designer as well and as you see VS unfortunately won't tell you what happened.
I'm having an issue where silverlight doesn't recognise custom controls or resources.
I include the namespace and intelisense recognises the item, the application builds fine and runs fine however the designer throws the following error.
The type 'x' was not found. Verify that you are not missing an assembly reference
and that all referenced assemblies have been built.
Usually I'm able to sort out the issue by performing a clean/rebuild of the project. however recently this route has been unable to resolve the issue.
Is this a known issue with the Visual Studio designer? are there any fixes/work arounds out there?
Thanks
EDIT:
I'm using the following declaration:
xmlns:converters="clr-namespace:x.Classes.Converters"
and referencing the control using the following:
<converters:ReportTypeImageConverter x:Name="ReportTypeImage"/>
Restarted visual studio this morning when I logged in and now its recognising the controls, which means I can use the designer again.
Try to go to your Project Properties and put some Reference Paths(folders where you .dll are)
Hope it Helps
Is there a way to debug Visual Studio or Blend so I can figure out where XAML designer load errors come from in my code?
The stack traces are often useless.
Thanks...
Use two VS2010 instances. Load one with your main app probject or a test harness application project and load the other with your controls project. Having built the controls project reference the debug dlls in your other project. Debugging from the VS2010 instance holding the controls project attach to the VS2010 instance holding the test application.
Place your break points as you like.
Now drive the test application instance of VS2010 as you would when building yout controls into an application, when your controls are load their code will execute and you can start stepping the code. You can do a similar thing when working with your controls in Blend just attach to the Blend instance.
In VS, first go to Debug->Exceptions and check the box for "Thrown" for CLR Exceptions. This will break into the debugger for exceptions caught by the Blend/VS app. Then do Debug->Attach To Process... and find the instance of Blend or devenv that has your solution open. Once the debugger starts up you can open the XAML file in the designer and debug against it.
Here are another two cents. Just make sure that the Options->Debugging->General->Enable Just My Code is unchecked in the instance you are using to attach to the designer's process.
I found both answers useful. Just adding my 2 cents - In the VS copy that you're using to attach to the designer, I needed to select the code type manually (Managed, v4.0 in my example) in the Attach To Process dialog to get the desired result. For some reason the default for devenv was Script, T-SQL. Looking at the date of the OP and original answers, it may be that an update to VS caused this change... just speculating.