Xaml error the name does not exist in the namespace

When you are writing your wpf code and VS tell that «The name ABCDE does not exist in the namespace clr-namespace:ABC». But you can totally build your project successfully, there is only a small inconvenience because you can not see the UI designing (or just want to clean the code).

Try to do these:

• In VS, right click on your Solution -> Properties -> Configuration Properties

• A new dialog is opened, try to change the project configurations from Debug to Release or vice versa.

After that, re-build your solution. It can solve your problem.

answered Aug 1, 2014 at 11:07

If the assembly is different from the namespace in which your class is contained, you have to specfiy it explicitly.

ex:-

xmlns:Local="clr-namespace:MusicPlayer.Controls;assembly=MusicPlayer"

In my case it was because of other compile errors. When other errors have been solved this seemingly related error was also removed from the list. Specially the errors at the bottom of the errors list and on pages you have recently changed.

So do not pay attention to this error directly and focus on other errors at first.

I’ve seen this issue go away by clearing the Xaml Design Shadow Cache. I had the issue with Visual Studio 2015 Update 1.

In Visual Studio 2015 the Cache is located here:

%localappdata%MicrosoftVisualStudio14.0DesignerShadowCache

Process:

1. Right-Click on the solution in the Solution Explorer and Choose «Clean Solution»
2. Shutdown Visual Studio
3. Delete the ShadowCache folder
4. Reopened the Visual Studio project
5. Rebuild the solution

And voila no more namespace errors.

answered Mar 3, 2016 at 18:44

Try changing the build target platform to x86 and building the project.

I noticed via Subversion that I apparently changed the project build Platform target to x64. This was the only change I had made. After making that change, the code was working for a short while before it started showing the same error you experienced. I changed the platform target to x86 to test and suddenly my designer was working again. Subsequently, I changed it back to x64, and the problem has disappeared completely. I suspect that the designer builds some kind of cached code in x32 and changing the x64 build platform breaks it when you make code changes.

answered Dec 26, 2014 at 22:00

Maybe another solution for when the project compiles but the XAML error is showing :

1. In solution explore, on the project node that contains the xaml
2. Right-click on the project and choose ‘Unload Project’
3. Right-click on the project and choose ‘Reload Project’
   Make sure that your project is still choosen as «startup project». If not :
4. Right-click on the project and choose ‘Set as startup project’

No need to rebuild, or close visual studio.

answered Mar 24, 2017 at 14:33

JonasJonas

1,1321 gold badge16 silver badges25 bronze badges

Dunno if this will help anyone else

I’m new to WPF and still a novice with VB.net — so I was assuming that getting this error was being caused by me doing summit silly…….. suppose I was really! I’ve managed to get rid of it by moving my project from a shared drive to one of my local drives.
Error’s disappeared, project compiles perfectly no further issues — yet. Looks like VS2015 still has problems with projects held on a shared drive.

answered Mar 14, 2016 at 18:12

gbdavidgbdavid

1,61917 silver badges38 bronze badges

I went through all the answers and none helped me. Finally was able to solve it by myself, so presenting the answer as it might help others.

In my case, the solution had two projects, one containing the models (say the project and assembly name was Models) and another containing the views and view models (as per our convention: project, assembly name and default namespace were Models.Monitor). The Models.Monitor referred Models project.

In the Models.Monitor project, in one of the xaml I included the following namespace:
xmlns:monitor=»clr-namespace:Models.Monitor»

I suspect that MsBuild and Visual Studio then were erroring out as they were trying to find a ‘Monitor’ type in the assembly ‘Models’. To resolve I tried the following:

1. xmlns:monitor=»clr-namespace:Models.Monitor;assembly=» — which is valid if the namespace is in same assembly as per https://msdn.microsoft.com/en-us/library/ms747086(v=vs.110).aspx
2. also tried the explicit namespace declaration:
   xmlns:monitor=»clr-namespace:Models.Monitor;assembly=Models.Monitor»

Neither of the above worked.

Finally I gave up, and as a work around moved the UserControl I was trying to use to another namespace: ‘ModelsMonitor’. I was able to compile fine after that.

answered Jun 2, 2017 at 19:07

answered Nov 26, 2018 at 12:10

answered Jun 2, 2013 at 13:55

answered Apr 30, 2019 at 20:30

Try verifying your assembly references. If you have a yellow exclamation mark on the project references there’s a problem there and you’ll get all kinds of errors.

If you know the project reference is correct, check the Target framework. For instance, having a project using the 4.5 framework reference a project with 4.5.2 framework is not a good combination.

answered Jul 22, 2016 at 7:44

The solution for me was to unblock the assembly DLLs. The error messages you get don’t indicate this, but the XAML designer refuses to load what it calls «sandboxed» assemblies. You can see this in the output window when you build. DLLs are blocked if they are downloaded from the internet. To unblock your 3rd-party assembly DLLs:

1. Right click on the DLL file in Windows Explorer and select Properties.
2. At the bottom of the General tab click the «Unblock» button or checkbox.

Note: Only unblock DLLs if you are sure they are safe.

answered Feb 21, 2017 at 15:15

Kevin CookKevin Cook

1,9021 gold badge17 silver badges16 bronze badges

SeanSean

2,3962 gold badges15 silver badges17 bronze badges

kad81kad81

10.6k3 gold badges39 silver badges44 bronze badges

user1040323user1040323

4694 silver badges11 bronze badges

This happened to me already twice in a complex WPF app, in it there are 4 multi platform projects, 1 shared project, 2 support libraries, and 1 test project..

This very specific XAML namespace error happened twice on very recently modified files on the Shared project. In both of my cases, it was a new c# file added with a repeating namespace entry;

Like namespace MyProgram.MyFolder.MyProgram.MyFolder

I double pasted it once by mistake, and once it was due to JetBrains Rider double pasting the namespace. (If you ever rename a project in Rider, it time to time starts double pasting namespaces on new file creations, especially on Shared projects..). These c# files with repeating namespaces were then called in the ViewModels where XAML files were referencing to. Well you then get these unrelated and misleading errors, you can have a problem with one file, all your Xaml files will start erroring out eventually.

Anyways, if you get these kind of errors, it’s most of the time an issue on a very newly added file or code change. My suggestions would be to look at your very recent changes.

answered Jun 17, 2020 at 19:43

answered Sep 30, 2013 at 14:57

jgongjgong

6611 gold badge6 silver badges6 bronze badges

R.T.R.T.

395 bronze badges

answered Jul 28, 2016 at 18:46

CeresCeres

3,4463 gold badges17 silver badges23 bronze badges

Kevin S. MillerKevin S. Miller

8931 gold badge9 silver badges21 bronze badges

When you are writing your wpf code and VS tell that «The name ABCDE does not exist in the namespace clr-namespace:ABC». But you can totally build your project successfully, there is only a small inconvenience because you can not see the UI designing (or just want to clean the code).

Try to do these:

• In VS, right click on your Solution -> Properties -> Configuration Properties

• A new dialog is opened, try to change the project configurations from Debug to Release or vice versa.

After that, re-build your solution. It can solve your problem.

answered Aug 1, 2014 at 11:07

If the assembly is different from the namespace in which your class is contained, you have to specfiy it explicitly.

ex:-

xmlns:Local="clr-namespace:MusicPlayer.Controls;assembly=MusicPlayer"

In my case it was because of other compile errors. When other errors have been solved this seemingly related error was also removed from the list. Specially the errors at the bottom of the errors list and on pages you have recently changed.

So do not pay attention to this error directly and focus on other errors at first.

I’ve seen this issue go away by clearing the Xaml Design Shadow Cache. I had the issue with Visual Studio 2015 Update 1.

In Visual Studio 2015 the Cache is located here:

%localappdata%MicrosoftVisualStudio14.0DesignerShadowCache

Process:

1. Right-Click on the solution in the Solution Explorer and Choose «Clean Solution»
2. Shutdown Visual Studio
3. Delete the ShadowCache folder
4. Reopened the Visual Studio project
5. Rebuild the solution

And voila no more namespace errors.

answered Mar 3, 2016 at 18:44

Try changing the build target platform to x86 and building the project.

I noticed via Subversion that I apparently changed the project build Platform target to x64. This was the only change I had made. After making that change, the code was working for a short while before it started showing the same error you experienced. I changed the platform target to x86 to test and suddenly my designer was working again. Subsequently, I changed it back to x64, and the problem has disappeared completely. I suspect that the designer builds some kind of cached code in x32 and changing the x64 build platform breaks it when you make code changes.

answered Dec 26, 2014 at 22:00

Maybe another solution for when the project compiles but the XAML error is showing :

1. In solution explore, on the project node that contains the xaml
2. Right-click on the project and choose ‘Unload Project’
3. Right-click on the project and choose ‘Reload Project’
   Make sure that your project is still choosen as «startup project». If not :
4. Right-click on the project and choose ‘Set as startup project’

No need to rebuild, or close visual studio.

answered Mar 24, 2017 at 14:33

JonasJonas

1,1321 gold badge16 silver badges25 bronze badges

Dunno if this will help anyone else

I’m new to WPF and still a novice with VB.net — so I was assuming that getting this error was being caused by me doing summit silly…….. suppose I was really! I’ve managed to get rid of it by moving my project from a shared drive to one of my local drives.
Error’s disappeared, project compiles perfectly no further issues — yet. Looks like VS2015 still has problems with projects held on a shared drive.

answered Mar 14, 2016 at 18:12

gbdavidgbdavid

1,61917 silver badges38 bronze badges

I went through all the answers and none helped me. Finally was able to solve it by myself, so presenting the answer as it might help others.

In my case, the solution had two projects, one containing the models (say the project and assembly name was Models) and another containing the views and view models (as per our convention: project, assembly name and default namespace were Models.Monitor). The Models.Monitor referred Models project.

In the Models.Monitor project, in one of the xaml I included the following namespace:
xmlns:monitor=»clr-namespace:Models.Monitor»

I suspect that MsBuild and Visual Studio then were erroring out as they were trying to find a ‘Monitor’ type in the assembly ‘Models’. To resolve I tried the following:

1. xmlns:monitor=»clr-namespace:Models.Monitor;assembly=» — which is valid if the namespace is in same assembly as per https://msdn.microsoft.com/en-us/library/ms747086(v=vs.110).aspx
2. also tried the explicit namespace declaration:
   xmlns:monitor=»clr-namespace:Models.Monitor;assembly=Models.Monitor»

Neither of the above worked.

Finally I gave up, and as a work around moved the UserControl I was trying to use to another namespace: ‘ModelsMonitor’. I was able to compile fine after that.

answered Jun 2, 2017 at 19:07

answered Nov 26, 2018 at 12:10

answered Jun 2, 2013 at 13:55

answered Apr 30, 2019 at 20:30

Try verifying your assembly references. If you have a yellow exclamation mark on the project references there’s a problem there and you’ll get all kinds of errors.

If you know the project reference is correct, check the Target framework. For instance, having a project using the 4.5 framework reference a project with 4.5.2 framework is not a good combination.

answered Jul 22, 2016 at 7:44

The solution for me was to unblock the assembly DLLs. The error messages you get don’t indicate this, but the XAML designer refuses to load what it calls «sandboxed» assemblies. You can see this in the output window when you build. DLLs are blocked if they are downloaded from the internet. To unblock your 3rd-party assembly DLLs:

1. Right click on the DLL file in Windows Explorer and select Properties.
2. At the bottom of the General tab click the «Unblock» button or checkbox.

Note: Only unblock DLLs if you are sure they are safe.

answered Feb 21, 2017 at 15:15

Kevin CookKevin Cook

1,9021 gold badge17 silver badges16 bronze badges

SeanSean

2,3962 gold badges15 silver badges17 bronze badges

kad81kad81

10.6k3 gold badges39 silver badges44 bronze badges

user1040323user1040323

4694 silver badges11 bronze badges

This happened to me already twice in a complex WPF app, in it there are 4 multi platform projects, 1 shared project, 2 support libraries, and 1 test project..

This very specific XAML namespace error happened twice on very recently modified files on the Shared project. In both of my cases, it was a new c# file added with a repeating namespace entry;

Like namespace MyProgram.MyFolder.MyProgram.MyFolder

I double pasted it once by mistake, and once it was due to JetBrains Rider double pasting the namespace. (If you ever rename a project in Rider, it time to time starts double pasting namespaces on new file creations, especially on Shared projects..). These c# files with repeating namespaces were then called in the ViewModels where XAML files were referencing to. Well you then get these unrelated and misleading errors, you can have a problem with one file, all your Xaml files will start erroring out eventually.

Anyways, if you get these kind of errors, it’s most of the time an issue on a very newly added file or code change. My suggestions would be to look at your very recent changes.

answered Jun 17, 2020 at 19:43

answered Sep 30, 2013 at 14:57

jgongjgong

6611 gold badge6 silver badges6 bronze badges

R.T.R.T.

395 bronze badges

answered Jul 28, 2016 at 18:46

CeresCeres

3,4463 gold badges17 silver badges23 bronze badges

Kevin S. MillerKevin S. Miller

8931 gold badge9 silver badges21 bronze badges

I am going to guess that this is a copy/paste inheritance error. Ha! You need to do two things. The first is to make sure you have referenced the Behaviors SDK in your project (right-click References, select Windows/Extensions/Behaviors SDK) and then add this to your xmlns at the top of your page:

      xmlns:Behaviors="using:Template10.Behaviors"
      xmlns:Core="using:Microsoft.Xaml.Interactions.Core"
      xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"

«After installing the Template10 upgrade, in a File->New project I named T10Minimal1.1 I get this error»

It wasn’t a copy paste situation. It was file new Template10 Minimal project.

    x:Class="Sample.Views.MainPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:Behaviors="using:Template10.Behaviors"
      xmlns:Core="using:Microsoft.Xaml.Interactions.Core"
      xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"
      xmlns:controls="using:Template10.Controls"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:local="using:Sample.Views"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      xmlns:vm="using:Sample.ViewModels" mc:Ignorable="d">

What’s with this yellow caution indicator? Is there a uwp windows 10 version of BehaviorsXamlSDKManaged? This one targets windows 8.1 Seems I’d get a warning or error from VS on this.

Also curious about the uppercase for the Behaviors, Core and Interactivity. Although I might prefer upper case isn’t it a generally accepted .XAML convention to use lower case?

 xmlns:Behaviors="using:Template10.Behaviors"
      xmlns:Core="using:Microsoft.Xaml.Interactions.Core"
      xmlns:Interactivity="using:Microsoft.Xaml.Interactivity"

I am having the same issue, but in main page. Designer crashes, but the project compiles despite errors.
This is a screen by @darenm so the issue must be wide.
The screen is from «Microsoft: DEV209.1x Developing Windows 10 Universal Apps — Part 1» and we are at least two people there with the same problem.

Acknowledged. Chasing it today.

Now I understand what your issue is.

Good news. The Behaviors SDK has a warning icon next to it because Visual Studio detects incompatibilities with UWP that in practice do not impact anything for us (developers). For what we use it for — behaviors — it is perfect. My screen also shows the warning, too.

To be clear this is a WARNING and not an ERROR.

The reason your designer is failing is something else. The reason might be simply because the designer is a little unstable at this point and requires a restart every day. Then again, it might be because your XAML has an error. It’s impossible to diag that at this point. But the Behavior SDK warning is okay.

Clean installed Windows 10, Visual Studio 2015 Enterprise — clean, not modified minimal template and the same thing happens to me so I guess it can’t be an error in XAML — Maybe it is «a little unstable designer» — nevertheless it compiles and works so it’s okay for now..

I’m facing the same issue here.

It seems that you target ARM.
Try to set to Any CPU when designing, rebuild and it should be OK

Solution: uninstall Template10 NuGet package, Clean solution and install it back.

Error reproduced here: http://1drv.ms/1Gpfd60

P.S.: namespaces should be a lower case anyway,
xmlns:Behaviors, Core, Interactivity

Having the same issue.

What worked for me was MichaelPetronlis’s solution. Thanks!

A quick note: I had to switch to Debug x64 to get the designer loading in VS2015.
For Blend however, I would still get the same error. Debug x86 got the Blend designer to
load there

So try out various configurations in both(!) VS and Blend if one or both of your designers are unhappy for some reason.

I get this error, i.e.

«The name ‘Interaction’ does not exist in the namespace «using:Microsoft.Xaml.Interactivity»

in many files in the XAMLBehaviorsSample project. I had set the target to x86 (from Arm, which was what it started as), but otherwise did not change anything. It compiles and runs though.

Make sure you do not use Behaviors SDK (XAML) version 12.0, which is for Windows 8.1.

What you need is the new open-sourced XamlBehaviors. You can include it by adding Microsoft.Xaml.Behaviors.Uwp.Managed to your project.json.

{
  "dependencies": {
    "Microsoft.NETCore.UniversalWindowsPlatform": "5.0.0",
    "Microsoft.Xaml.Behaviors.Uwp.Managed": "1.0.3",
    "Template10": "1.1.3",
    "Newtonsoft.Json": "8.0.2"
  },

Thanks Justin, the project did have the right version of XamlBehaviors — 1.0.3 was listed in the .json file (the XAMLBehaviorsSample actually came from the UWP XamlBehaviors project on Github). I did fix the problem though, in Solution Explorer there were references to Microsoft.Xaml.Interactivity and Microsoft.Xaml.Interactions.Core; they both had the exclamation mark beside them so I removed them, then added the references back from Object Browser (v1.0.3.0 req’d for Win 10 UWP as opposed to the identically named v12.0.0.0 which supports Win 8.1). They do not show up in the project’s References list now, but I don’t get those error messages in the XAML file.

Haven’t managed to remove the error from my own UWP project yet though; there are no references to .Interactivity or .Interactions in my project References to remove. Adding v1.0.3.0 of both of them from Object Browser does let it compile and run though (and it behaves as expected), but in the XAML file it shows them as errors.
Thanks!

So, turns out I just needed to restart Visual Studio to get it to stop giving me «The name ‘Interaction’ does not exist in the namespace» errors for the XAML file. When in doubt, reboot!

@TCPhelps This worked for me as well! Thanks!!

@TCPhelps Thanks!!! This worked for me too. Additionally I have to manually delete the bin & obj folder and rebuild it. 😄