The name does not exist in the namespace error in XAML

Question

Using VS2012 working on a VB NET WPF application    I have a simple MusicPlayer tutorial app I am using to learn WPF    I am converting a C  version of the tutorial to VB NET step by step   It has 2 classes in the app that are both under the same namespace   I am able to reference the namespace in the XAML but when I try to reference the class object in XAML I get an error and I am not able to compile   Strange thing is that the IntelliSense works fine with both referencing the namespace via the xmlns c  tag and also when typing the class object using   lt c   But the object is underlined and errors are generated trying to build or work in the designer   The  vb  class files are in a folder called  Controls   The Main project Root Namespace is intentionaly left blank    The class is coded like this     Namespace MusicPlayer Controls     Public Class UpdatingMediaElement             code here     End Public End Namespace   The xaml looks like this   namespace defined in the  lt Window  gt  tag  xmlns c  clr-namespace MusicPlayer Controls     object defined in a  lt Grid gt        lt c UpdatingMediaElement Name  MyMediaElement    gt     error displayed  The name  UpdatingMediaElement  does not exist in the namespace  clr-namespace MusicPlayer Controls    Not sure what is wrong or how to fix it

User · Answer

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

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I had the same symptoms  The name does not exist in the namespace error   but the cause turned out to be different  I had a C  drive crash and had to reinstall Visual Studio 2017  I restored my source code files and opened the solution  Built it  No dice  As well as the  Name does not exist in the namespace  errors I noticed my sub-projects complaining that they couldn t find a MyProject cs file   MyProject  is not the actual project name  just used here as an example   I had a hunt for where MyProject cs had gone  then remembered that there was never any such file  I looked in the Properties folders of each sub-project and found that Visual Studio had off its own back added bogus references to MyProject cs   I removed these references and now the solution builds fine like it used to

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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

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A combination of two ideas in this thread worked for me  so I ll post what I did in the hopes that it helps someone else over the next 5 years that this problem continues  I m using VS2017 Community    Delete reference to dll Clean  Rebuild  Build Close VS  Unblock the dll  see note below   Delete shadow cache Open VS  Clean  Rebuild  Build Restore reference to dll Clean  Rebuild  Build   I may not have the order exactly right in steps 2  4  and 6 but I was grasping at straws after spending nearly 2 hours with this problem  I think the key for me was the combination of removing the reference  unblocking the dll and deleting the shadow cache    Note for step 3 - The dll I m using was written by a coworker mentor of mine  so I know it s safe  Careful with this step if you don t know the source of your dll    I ll be bookmarking this thread for posterity  since it appears that MS has no desire to clean this stuff up  WPF is hard enough to learn on it s own  and having to hack through stuff like this when you ve done everything right is infuriating

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In Visual Studio 2019 I was able to fix it by changing the dropdown to Release as recommended in other answers  But when I changed back to Debug mode the error appeared again    What fixed it for me in Debug mode    Switch to Release mode Click on  Disable project code  in the XAML Designer      Switch back to Debug mode    the error is gone

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Jesus    This is still a problem five years later in Visual Studio 2017  Since I m new to WPF  I was sure the problem was somehow me  but no  everything compiled and ran correctly   I tried rebuilding  cleaning and rebuilding  switching between x86 x64 output  rebooting Windows  cleaning the ShadowCache folder  adding   assembly  my main assembly name   to the XML namespace declaration  nothing worked  The single thing that did   Put my static class of Commands  in my case the deal was about making the design discover my WPF Commands  in its separate assembly and changing the assembly name to that one s instead

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Another possible cause  A post-build event is removing the project DLL from the build folder   To clarify  WPF designer may report  The name XXX does not exist in the namespace      even when the name does exist in the namespace and the project builds and runs just fine if a post-build event removes the project DLL from the build folder  bin Debug  bin Release  etc    I have personal experience with this in Visual Studio 2015

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In my case  this problem will happen when the wpf program s architechture is not exactly same with dependency  Suppose you have one dependency that is x64  and another one is AnyCPU  Then if you choose x64  the type in AnyCPU dll will  does not exist   otherwise the type in x64 dll will  does not exist   You just cannot emilate both of them

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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    Right click on the DLL file in Windows Explorer and select Properties  At the bottom of the General tab click the  Unblock  button or checkbox    Note  Only unblock DLLs if you are sure they are safe

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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

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The same problem plagues Visual Studios 2013  Service Pack 4  I also tried it with Visual Studios 2015 Preview with the same results   It s just a limitation of the WPF visualizer which the Visual Studios team hasn t fixed  As proof  building in x86 mode enables the visualizer and building in x64 mode disables it   Strangely enough intellisense works for Visual Studios 2013  Service Pack 4

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In my case the problem was due to some phantom files under the project s obj directory  The following fixed the issue for me    Clean project Exit VS rm -rf  obj   Invoke VS and rebuild

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I had this problem recently using VS 2015 Update 3 for my WPF project in  NET 4 6 2  The copy of my project was in a network folder  I moved it locally and that solved the problem   This may solve other sort of problems  as it looks like VS 2015 doesn t like network paths  Another issue that is a big problem for them is syncing git repositories if my project is in a network path  also solved by moving it locally

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Add an empty constructor for your view model and rebuild solution

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Maybe another solution for when the project compiles but the XAML error is showing      In solution explore  on the project node that contains the xaml  Right-click on the project and choose  Unload Project  Right-click on the project and choose  Reload Project  Make sure that your project is still choosen as  startup project   If not   Right-click on the project and choose  Set as startup project    No need to rebuild  or close visual studio

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Adding to the pile   Mine was the assembly name of the WPF application was the same assembly name as a referenced dll  So make sure you don t have duplicate assembly names in any of your projects

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Try checking the References section  and see if there is a warning icon over the library reference you included     If you see it then go to the Project -  Properties -  Application and make sure that both libraries are targeting the same version of the  NET framework   P S  When this issue happens it can also be noticed from the Warnings section

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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

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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    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 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

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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

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As another person posted this can be caused by saving the project on a network share   I found that if I switched from using a network path to a mapped network drive everything worked fine   from     SERVER Programming SolutionFolder   to    Z  Programming SolutionFolder   exact mapping optional

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In the solution property page  check the platform of the assembly that contains  UpdatingMediaElement  and the assmeblies that contain any of the superclasses and interfaces from which  UpdatingMediaElement  subclasses or implements  It appears that the platform of all these assemblies must be  AnyCPU

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VB NET does not automatically add the Namespace information based on the folder structure as it does in C    I think I am going through the same tutorial as you  Teach Yourself WPF in 24 Hours   and doing the same conversion to VB   I found you have to manually add the Namespace information to Both the XAML Class and the XAML VB code behind to be able to use the Namespaces as described in the book   Even then  VB doesn t automatically Assign the Namespace to the Assembly as it does in VB   There is another article here that shows how to include this in your project templates so it does build the Namespace information automatically -  Automatically add namespace when adding new item

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In my particular case  the problem looks like a bug in Visual Studio - because the error didn t make any sense  This is what worked for me  perhaps it may work for you as well   Solution  Try Re-building the solution  Short cut to re-build  CTRL   SHIFT   B

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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

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In my case  the user control was added to the main project   I tried various solutions above to no avail  Either I would get Invalid Markup but the solution would compile and work  or I would add the  xmlns c  clr-namespace MyProject assembly MyProject  and then the markup would show  but I would get a compile error that the tag does not exist in the XML namespace   Finally  I added a new WPF User Control Library project to the solution and moved my user control from the main project into that one  Added the reference and changed the assembly to point to the new library and finally the markup worked and the project compiled without error

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I had the added the assembly as a project - first deleted the ddl that was added specifically to the references to the dll - that did it

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This problem can also be caused if the assembly that you re referencing isn t actually built  For example  if your xaml is in Assembly1 and you re referencing a class also in Assembly1  but that assembly has errors and isn t building  this error will be shown   I feel silly about it  but in my case I was tearing asunder a user control and had all sorts of errors in the related classes as a result  As I was attempting to fix them all I started with the errors in question  not realising that xaml relies on built assemblies to find these references  unlike c  vb code which can work it out even before you build

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I had the solution stored on a network share and every time I opened it I would get the warning about untrusted sources  I moved it to a local drive and the  namespace does not exist  error went away as well

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I m also having a lot of trouble with this one  Intellisense helps me complete the namespace and everything  but the compiler cries  I ve tried everything I found in this and other threads  However in my case what helped in the end was writing something like this   xmlns util  clr-namespace LiveSpielTool Utils assembly     Leaving the assembly name empty  No idea why  But it was mentioned here  I must add I am developing an assembly  so the assembly attribute might make sense  But entering the assembly name did not work  So weird

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In my case I had a namespace and class spelled exactly the same  so for example  one of my namespaces was  firstDepth secondDepth Fubar   which contains its own classes  e g  firstDepth secondDepth Fubar someclass   but I also had a  Fubar  class in the namespace  firstDepth secondDepth   which textually resolves to the same as the Fubar namespace above   Don t do this

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Ok  so none of these tips worked for me  unfortunately  I was able to eventually solve the issue  It seems that Visual Studio does not play nicely with network drives  I solved this issue by moving the project from the shared drive to my local and recompiled  No more errors

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I had the same problem   and in my case the the Markup Design View asked me to rebuild the solution and did not show me the form layout with this message  Design view is unavailable for x64 and ARM target platforms  or Build the Project to update Design view   It does not get solved by rebuilding the solution  neither the design view nor the  The name does not exist in the namespace  error   I think it was because I had played with the settings on Solution -  Properties   Configuration Properties  I finally resolved the problem with 2 jobs    Checking all check boxes on Build Column of the page  Solution -  Properties -  Configuration Properties Changing the solution configurations from Debug to Release or vice versa    I think it s a bug in Visual Studio2012 Update 2

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I get this problem all the time  My views are in a WPF Custom Control Library project  a variant on Class Library   I can reference pre-built assemblies  but cannot reference any code in another project of the same solution  As soon as I move the code to the same project as the xaml it s recognized

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Also try to right click on your project- properties and change Platform target to Any CPU and rebuild  it will then work  This worked for me

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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

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Looks like this problem may be solved through a variety of  tricks    In my case  I had been building rebuilding cleaning the entire solution  instead of just the project that I was working on within the solution  Once I clicked  Build  my project    the error message went away

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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  Microsoft VisualStudio 14 0 Designer ShadowCache   Process    Right-Click on the solution in the Solution Explorer and Choose  Clean Solution  Shutdown Visual Studio Delete the ShadowCache folder Reopened the Visual Studio project Rebuild the solution   And voila no more namespace errors

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If non of the answers worked For me was  Net Framework version compatibility issue of the one i m using was older then what is referencing  From properties   gt  Application then  target framework

[wpf] The name does not exist in the namespace error in XAML

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