I know this is a recurring error but I can't seem to get around it.
Intellisense does recognize the name of my custom control and suggests to add the proper using: directives, but not only XAML designer doesn't find the name of the control but I can't get through compilation either.
The custom control is a public class defined as
namespace MyApp.CustomControls
{
public class CustomTextBox : TexBox
{
...
}
}
And in my MainPage.xaml
<Page ...
xmlns:customControls="using:MyApp.CustomControls">
...
<customControls:CustomTextBox/>
...
</Page>
This does not render in design nor compile.
This answer and the ones below are not working for me.
The error message:
Error XDG0008 The name "CustomTextBox" does not exist in the namespace "using:MyApp.CustomControls".
Your code should works well after you build the project, and it works well in my side using your above code. Try to clean your solution or delete the bin and obj folders in your project then rebuild your app again. Also try to restart your Visual Studio. If it still happens, you can provide a reproducible sample to help me look into this issue.
I've seen quite a lot solutions saying that you should rebuild the project, restart Visual Studio or restart the machine.
What worked for me was specifying the assembly in the namespace reference, that is:
xmlns:the_namespace="clr-namespace:the_namespace" - produces the above error.
xmlns:the_namespace="clr-namespace:the_namespace;assembly=the_assembly" - works well.
I got a version of this error in my embedded UserControl when I tried to use the Name property in my XAML instead of using x:Name. In other words, when my XAML code looked like this:
myUserControls="using:MyUserControls"
<myUserControls:GraphCanvas Name="GraphCanvas" />
I got an error that 'The name "GraphCanvas" does not exist in the namespace "using:MyUserControls"'. When I changed one line of code to this:
<myUserControls:GraphCanvas x:Name="GraphCanvas" />
Everything built just fine.
I'm dropping this solution here because it took me about a day and a half to figure out this problem and this was the only stackoverflow page I found when I searched the error string. Hopefully I will save someone else the hassle I went through.
Related
I've attempted to start playing with .Net MAUI and I've setup my development environment following the steps as described in:
https://learn.microsoft.com/en-us/dotnet/maui/get-started/first-app?pivots=windows
https://learn.microsoft.com/en-us/windows/apps/project-reunion/set-up-your-development-environment#required-workloads-and-components
https://learn.microsoft.com/en-us/xamarin/android/get-started/installation/android-emulator/device-manager?tabs=windows&pivots=windows
I've also run the 'maui-check' CLI tool and everything checks out, but when I create a new .NET MAUI App with Visual Studio 2019 v16.11.0 Preview 2.0 (running on Windows 10 Home 20H2), I get the 'The name 'InitializeComponent' does not exist in the current context' build errors. It also doesn't find the references to any controls on the form e.g. 'The name 'CounterLabel' does not exist in the current context'
I've tried almost everything in this post The name 'InitializeComponent' does not exist in the current context which contains suggestions like adding and removing files, making changes and changing them back... basically everything except throwing a penny in a wishing well.
I found that a common mistake is a namespace mismatch, but here is what I have showing that the namespaces are correct:
App.xaml:
<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MauiApp1"
x:Class="MauiApp1.App">
...
</Application>
App.xaml.cs
using Microsoft.Maui;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.PlatformConfiguration.WindowsSpecific;
using System;
using Application = Microsoft.Maui.Controls.Application;
namespace MauiApp1
{
public partial class App : Application
{
public App()
{
InitializeComponent(); <-- This is throwing the build error...
}
protected override IWindow CreateWindow(IActivationState activationState)
{
this.On<Microsoft.Maui.Controls.PlatformConfiguration.Windows>()
.SetImageDirectory("Assets");
return new Microsoft.Maui.Controls.Window(new MainPage());
}
}
}
MainPage.xaml:
ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MauiApp1.MainPage"
BackgroundColor="{DynamicResource PageBackgroundColor}">
...
</ContentPage>
MainPage.xaml.cs
using System;
using Microsoft.Maui.Controls;
namespace MauiApp1
{
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent(); <-- This is throwing the build error...
}
int count = 0;
private void OnCounterClicked(object sender, EventArgs e)
{
count++;
CounterLabel.Text = $"Current count: {count}"; <-- This is throwing the build error...
}
}
}
Any help will be greatly appreciated!
---=== UPDATE ===---
The path to the project I created is c:\develop\c#...... as soon as I copy the project to a folder that doesn't contain 'c#' it works. This clearly causes some parsing in the background to fail.
I faced the same issue and looks like when I created a ContentPage in VS its still pointing to Xamarin Forms. After changing namespace to MAUI, I updated the Build Action(RightClick on Xaml Page>>Properties>>BuildAction) of XAML Page to MauiXaml and it worked for me.
Close VS2022
Open VS2022
Open project with menu VS2022(File - Open - Project...)
What caused it for me was that I had renamed the xaml and xaml.cs file something else but I hadn't updated it in the ContentPage node in the xaml under x:Class
The same error popped in for me being an absolute beginner and missing the ending '>' in the XAML file. So, It could also be XAML errors, which leads to this error.
The path to the project I created is c:\develop\c#...... as soon as I copy the project to a folder that doesn't contain 'c#' it works. This clearly causes some parsing in the background to fail.
A very simple answer but has happened to me a few times.
Make sure you are using the preview version of VS 2022. It is very easy to accidently open up any other version of VS, which will cause the error to occur.
I have found a workaround for this problem. I am a newbie to c# and especially to .net Maui therefore, my apologies if I misinterpreted things differently.
First things first The error is about the context that the InitializeComponent() resides in. Context is nothing but the nuget package dependency that the file is looking for.
To change the context
Open the .cs file and at the top of the editor click the navigation bar as shown in the
Image
Change the context to Windows specific dependency from the list.
And also the other workaround would be to change the build action of the xaml file to MauiXaml as others mentioned
I'm using VS 2022 Preview 17.4.0 Preview 1.0, I don't know why but when you create a new Content Page it creates with the wrong namespace. take a look in the C# file and fix the namespace. It worked for me.
I am using preview version of 17.5 VS2022, I add to do below changes to run the app after adding new page.
*.Xmal Build Action -> BundleResource
*.Xmal.cs Build Action -> Compile
I've attempted to start playing with .Net MAUI and I've setup my development environment following the steps as described in:
https://learn.microsoft.com/en-us/dotnet/maui/get-started/first-app?pivots=windows
https://learn.microsoft.com/en-us/windows/apps/project-reunion/set-up-your-development-environment#required-workloads-and-components
https://learn.microsoft.com/en-us/xamarin/android/get-started/installation/android-emulator/device-manager?tabs=windows&pivots=windows
I've also run the 'maui-check' CLI tool and everything checks out, but when I create a new .NET MAUI App with Visual Studio 2019 v16.11.0 Preview 2.0 (running on Windows 10 Home 20H2), I get the 'The name 'InitializeComponent' does not exist in the current context' build errors. It also doesn't find the references to any controls on the form e.g. 'The name 'CounterLabel' does not exist in the current context'
I've tried almost everything in this post The name 'InitializeComponent' does not exist in the current context which contains suggestions like adding and removing files, making changes and changing them back... basically everything except throwing a penny in a wishing well.
I found that a common mistake is a namespace mismatch, but here is what I have showing that the namespaces are correct:
App.xaml:
<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MauiApp1"
x:Class="MauiApp1.App">
...
</Application>
App.xaml.cs
using Microsoft.Maui;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.PlatformConfiguration.WindowsSpecific;
using System;
using Application = Microsoft.Maui.Controls.Application;
namespace MauiApp1
{
public partial class App : Application
{
public App()
{
InitializeComponent(); <-- This is throwing the build error...
}
protected override IWindow CreateWindow(IActivationState activationState)
{
this.On<Microsoft.Maui.Controls.PlatformConfiguration.Windows>()
.SetImageDirectory("Assets");
return new Microsoft.Maui.Controls.Window(new MainPage());
}
}
}
MainPage.xaml:
ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MauiApp1.MainPage"
BackgroundColor="{DynamicResource PageBackgroundColor}">
...
</ContentPage>
MainPage.xaml.cs
using System;
using Microsoft.Maui.Controls;
namespace MauiApp1
{
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent(); <-- This is throwing the build error...
}
int count = 0;
private void OnCounterClicked(object sender, EventArgs e)
{
count++;
CounterLabel.Text = $"Current count: {count}"; <-- This is throwing the build error...
}
}
}
Any help will be greatly appreciated!
---=== UPDATE ===---
The path to the project I created is c:\develop\c#...... as soon as I copy the project to a folder that doesn't contain 'c#' it works. This clearly causes some parsing in the background to fail.
I faced the same issue and looks like when I created a ContentPage in VS its still pointing to Xamarin Forms. After changing namespace to MAUI, I updated the Build Action(RightClick on Xaml Page>>Properties>>BuildAction) of XAML Page to MauiXaml and it worked for me.
Close VS2022
Open VS2022
Open project with menu VS2022(File - Open - Project...)
What caused it for me was that I had renamed the xaml and xaml.cs file something else but I hadn't updated it in the ContentPage node in the xaml under x:Class
The same error popped in for me being an absolute beginner and missing the ending '>' in the XAML file. So, It could also be XAML errors, which leads to this error.
The path to the project I created is c:\develop\c#...... as soon as I copy the project to a folder that doesn't contain 'c#' it works. This clearly causes some parsing in the background to fail.
A very simple answer but has happened to me a few times.
Make sure you are using the preview version of VS 2022. It is very easy to accidently open up any other version of VS, which will cause the error to occur.
I have found a workaround for this problem. I am a newbie to c# and especially to .net Maui therefore, my apologies if I misinterpreted things differently.
First things first The error is about the context that the InitializeComponent() resides in. Context is nothing but the nuget package dependency that the file is looking for.
To change the context
Open the .cs file and at the top of the editor click the navigation bar as shown in the
Image
Change the context to Windows specific dependency from the list.
And also the other workaround would be to change the build action of the xaml file to MauiXaml as others mentioned
I'm using VS 2022 Preview 17.4.0 Preview 1.0, I don't know why but when you create a new Content Page it creates with the wrong namespace. take a look in the C# file and fix the namespace. It worked for me.
I am using preview version of 17.5 VS2022, I add to do below changes to run the app after adding new page.
*.Xmal Build Action -> BundleResource
*.Xmal.cs Build Action -> Compile
So I've been working on a project and things were going fine until a NullReferenceException: Object reference not set to an instance of an object error began popping up only in the XAML designer for a View along with the stack trace. The project would run fine however.
To find the cause of this error I began commenting out code in both the offending View and ViewModel. Doing this would give inconsistent and odd results where I ended up with nearly all of the code commented out.
For instance, this would cause the error:
private async void FirmwareUpdateAsync()
{
bool isOK = true;
isOK = await Task.Run(() => _usb.DeviceHandshakeAsync());
if (!isOK)
{
// Left Empty
}
}
But this would not:
private async void FirmwareUpdateAsync()
{
bool isOK = true;
isOK = await Task.Run(() => _usb.DeviceHandshakeAsync());
/*if (!isOK)
{
// Left Empty
}*/
}
I spent two days trying to figure this out and trying to track down the exact cause when the error seemed to evolve into
Could not load file or assembly'[ProjectName], version=0.0.0.1, Culture=neutral, PublicKeyToken=null". The system cannot find the specified folder
and
Type reference cannot find type named'{clr-namespace:[ProjectName].ViewModels.SubViewModels;assembly = [ProjectName]}ErrorViewModel.
Again, this only occurs in the XAML designer and the line numbers for these errors are the declarations of the viewModels and subviews:
<Page.DataContext>
<vm:Pg7FirmwareUpdateViewModel/> <= Here
</Page.DataContext>
<Page.Resources>
<!-- Sets Progress Bar View -->
<DataTemplate DataType="{x:Type svm:ErrorViewModel}"> <= Here
<sv:ErrorView/>
</DataTemplate>
</Page.Resources>
Oddly, the number of these errors depends on how many views I open (always in the declarations), plus I can still run the project.
No amount of building or rebuilding or cleaning seems to matter, I've verified the project's dll is in the bin folder, I tried but failed to use fuslogvw (Can't figure out how to get a log for the project, I only managed to capture something with PowerShell.exe that I wasn't using), and I've looked at all of the 150+ questions on these errors I could find. Any clue what I should do to fix this?
UPDATE: After thinking about Mark's answer below, I excluded from project & moved the suspect View and ViewModels, and replaced them with brand new files of the same name. Everything seems OK until I add back the DataContext again. Is there a way the project can get corrupted so even though I'm cleaning and rebuilding the solution, VS is using bad data or something? This is maddening.
UPDATE2: Rather than blindly stab in the dark I figured I'd just copy all the files to a new folder and revert to my last commit which was working fine, then just copy the changes in and try again. After reverting I built old project and I have the same exact problem before attempting to copy in the new files!
That has to point to a corrupt file or something no?
The view is being created by the XAML designer, and since you've declared your data context in XAML it's creating an instance of that as well. Something in your vm:Pg7FirmwareUpdateViewModel isn't running properly, and that's what causing the error. Can't really help any further without seeing the source code for that class.
This is why things like MVVM Light expose a IsInDesignMode property, so you can ensure that problematic portions of your code won't be executed in designer.
I finally gave up and just started a project and copied in all of the old files. When I finished this, I was back at the old "NullReferenceException" where the XMAL wouldn't display. Progress, ha.
What the problem appears to be was a constructor for displaying error messages. In the constructor I was passing an enum as an argument without doing anything with it:
public class ErrorMessageModel
{
public ErrorMessageModel(ErrorCodes errorcode, string errorName,
string errorDescription, string errorTips)
{
ErrorName = errorName;
ErrorDescription = errorDescription;
ErrorTips = errorTips;
}
}
After removing ErrorCodes errorcode the XMAL Designer is working again and things seem stable.
I'm getting designer error on code:
The Component i'm willing to define a List of properties for:
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;
namespace TestProjectForProperty.Test
{
public class MyTreeView : TreeView
{
private List<TypeDescriptorBase> _descriptorsAvailable = new List<TypeDescriptorBase>();
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public List<TypeDescriptorBase> DescriptorsAvailable
{
get { return _descriptorsAvailable; }
set { _descriptorsAvailable = value; }
}
}
}
The Descriptor itself:
using System;
namespace TestProjectForProperty.Test
{
[Serializable]
public class TypeDescriptorBase
{
public string Name { get; set; }
public override string ToString()
{
return Name;
}
}
}
I am getting the following error if i try to use the component for example on a form and add any items on the property sheet or in the component's constructor to the DescriptorsAvailable property
Error 1 Invalid Resx file. Could not load type
System.Collections.Generic.List`1[[TestProjectForProperty.Test.TypeDescriptorBase,
TestProjectForProperty, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null]], mscorlib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089 which is used in the .RESX file.
Ensure that the necessary references have been added to your project.
Line 134, position 5. ...\visual studio
2010\Projects\TestProjectForProperty\TestProjectForProperty\Form1.resx 134 5 TestProjectForProperty
In the Resx file there is data field with base64 encoded stuff inside when this error is present.
I have been searching for an answer, but the best i got is to restart everything, it didn't help me, do you guys have any suggestions? I'm using .net 4 client and visual studio 2010
In my experience, this is due to a change of version of a referenced library, or a change of the lib itself, which contains the backing type of a property you have defined in your user control. The solution is to "force" the visual studio designer to re-initialize it's designer code for that type, and not expect to retrieve a "canned" version of it from the .resx file of the control.
1) Delete the offending data section in the .resx file of your control. This will be a section in the xml of the .resx file associated with your user control, which has a node: <data></data> - the name attribute will be set to whatever you've named that object in the properties of whatever you added this type to. The <data>/data> section contains a base64 encoded string that is the encoded form of the name and version of the library the type comes from. This is where the problem ism, because it now contains an encoded version of the library and/or version number you are no longer referencing in order to include the type. Delete the entire <data>/data> section, from opening to closing tag, save the change and close the file. Now the "artifact" is gone.
2) Now find the place in the designer file for your control, where the type is instantiated; this is initialization code generated for you by visual studio, and it is the place that is expecting to load a "canned" definition of the type from the base64 encoded string contained within the .resx file. The line will look something like this:
this.myCtrlFoo.MyPropertyFroo = ((MyNamespaceFoo.MyTypeFoo)(resources.GetObject("myCtrlFoo.MyPropertyFroo")));
...now just replace the resources.GetObjec call with the instantiation of a new instance of the appropriate type like so:
this.myCtrlFoo.MyPropertyFroo = ((MyNamespaceFoo.MyTypeFoo)(new MyNamespaceFoo.MyTypeFoo()));
...now save the change to the file, close it, rebuild, and everything should now build & run OK.
Put the MyTreeView and TypeDescriptorBase classes into another project and reference it from your GUI project will resolve the issues.
I'm not sure why exactly the problem occurs - I guess it has something to do with the way the serializing process is generating the base64 string for the DescriptorsAvailable Property. Maybe somebody else can give us some insight.
I've struggled quite a bit with this; I have three user controls that all expose the same non-designer property, but for some reason, any change to two of the three would instantly cause the next build to fail with this same issue. This is in VS 2015.
I wound up having to add the following two attributes to the property that kept expanding in the resx file, and it hasn't occurred since. It works for me because they're not available in the designer anyway.
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
For me, this error occured when I used a custom class as a property for the user control. When I switched from property to traditional get- and set- methods, the error disappeared. I guess this is because properties are already compiled at design-time, so when you build the whole project, a new version of the custom class is compiled which is separate from the one of the control, and the reference is broken.
For me, with the custom class Inventory, all I had to do was to switch from this property-based approach:
public Inventory Resources {get;set;}
to this method-based approach:
private Inventory resources;
public Inventory getResources() { return resources; }
public void setResources(Inventory newResources) { resources = newResources; }
I hope this helps someone, as I've been spending some hours on figuring it out.
In my case I've got the error : "error MSB3103: Invalid Resx file. The specified module could not be found" executed in a light windows container based on mcr.microsoft.com/powershell instead of mcr.microsoft.com/windows:1909 (was working fine on 1909).
The error was on a ressource icon that was compressed with PNG inside.
It can be checked by opening the ressource on visual studio : Project > Properties > Ressources.resx, select icons, double click on the icon, check the end of the title that is either "..,BMP]" or "...,PNG]").
Updating the icon with an uncompressed format solve the "Invalid Resx file" issue.
I stumbled across this question today whilst looking for the solution to a similar issue.
Unfortunately none of the above worked for me, however my issue turned out to be that I had different versions of the .NET Framework for different projects. For example;
Project A - .NET Framework 4.7.2
Project B - .NET Framework 4
Where Project B was referencing Project A. Solution was simply to change the .NET Framework version of Project B to 4.7.2 (in my case) and hey presto the issue was resolved.
A shame Visual Studio doesn't provide a more helpful error message in this case, but something to look out for!
I am starting a new project and oriented my projectstructure on the structure recommended in this question.
Now I am seeing strange behaviour. When I am setting the datacontext in the View-XAML, it isn't found at runtime (getting a XamlParseException). When I set it in the constructor in the codebehind-file, everything is working just fine.
Is this official (documented) behaviour when using different assemblies, or am I doing something wrong?
The code:
Not Working:
MainView.xaml:
<UserControl x:Class="ViewsRoot.Views.MainView"
xmlns:baseControls="clr-namespace:BaseControls;assembly=BaseControls"
xmlns:viewModels="clr-namespace:ViewModelsRoot;assembly=ViewModelsRoot">
<UserControl.DataContext>
<viewModels:ShellViewModel />
</UserControl.DataContext>
MainView.xaml.cs
public MainView()
{
InitializeComponent();
// No DataContext set in codebehind-file
}
Working:
MainView.xaml:
<UserControl x:Class="ViewsRoot.Views.MainView"
xmlns:baseControls="clr-namespace:BaseControls;assembly=BaseControls"
xmlns:viewModels="clr-namespace:ViewModelsRoot;assembly=ViewModelsRoot">
<!--<UserControl.DataContext>
<viewModels:ShellViewModel />
</UserControl.DataContext> -->
MainView.xaml.cs:
public MainView()
{
InitializeComponent();
DataContext = new ViewModelsRoot.ShellViewModel();
}
Update:
The Exception-Text is:
{"The file or assembly \" ViewModelsRoot, PublicKeyToken = null \ "or one of its dependencies was not found. The system can not find the file specified."}
And the only inner Exception I can see is a System.IO.FileNotFoundException.
Update 2:
Thanks for the comments, but I haven't forgotten a namespace. I shortened it here for showing the code, but I double- and triplechecked (again). The DataContexts namespace is also filled in by intellisense. The whole <viewModels:ShellViewModel /> is written by intelli-sense. So it is found at designtime... ...so any more ideas?
Update 3:
The xaml is "correctly" parsed as I am able to bind the DataContext to a class in the same assembly.
I have reproduced this error using a three project solution, with the specified dependencies between them:
StartupProject → ViewsRoot
ViewsRoot → ViewModelsRoot
ViewModelsRoot
"StartupProject" has "exe" output type, while the other two have "dll".
In my case, I solved the problem by adding "ViewModelsRoot" to the References list of "StartupProject". It is not a coding problem, but rather a runtime problem, because "ViewModelsRoot.dll" is not copied to "StartupProject" output folder.
When you specify the DataContext in code-behind, Visual Studio notices the need for that "dll" and adds it to the output after compilation. This doesn't happen when setting the DataContext from XAML. It is tricky because "ViewModelsRoot" code is used from XAML with Reflection. Adding it to References list forces Visual Studio to copy the "dll" in both cases.
You can also copy "ViewModelsRoot.dll" to the output folder directly, but it will not be updated when you change the code.
I've often found this error when the project target framework was set to "Client Profile" (this was set by default on VS2010, IIRC), if this is the case, try changing it to 3.5 or 4.0.