c# - InitializeComponent() Cannot locate resource based on system language

The application was developed on machines running windows 10, with the system language set to our local language, danish. Now we are at a stage where the software needs to be used in offices in other countries.
However, the view crashes on startup on those machines, and I have found out that if I change the system language on my own machine, it will not work for me either.
Why this is, we can't figure out.

Error message from InitializeComponent:

System.IO.IOException: 'Cannot locate resource 'views/main/mainview.xaml'.'

StackTrace:

at MS.Internal.AppModel.ResourcePart.GetStreamCore(FileMode mode,
FileAccess access) at
System.IO.Packaging.PackagePart.GetStream(FileMode mode, FileAccess
access) at System.IO.Packaging.PackagePart.GetStream() at

System.Windows.Application.LoadComponent(Object component, Uri
resourceLocator) at
InfoCenter.Views.Main.MainView.InitializeComponent() in
D:\Workspace\Visual Studio\MT Info Center WPF\Info
Center\Views\Main\MainView.xaml:line 1 at
InfoCenter.Views.Main.MainView..ctor() in D:\Workspace\Visual
Studio\MT Info Center WPF\Info Center\Views\Main\MainView.xaml.cs:line
21 at InfoCenter.App.OnStartup(StartupEventArgs e) in
D:\Workspace\Visual Studio\MT Info Center WPF\Info
Center\App.xaml.cs:line 57 at

System.Windows.Application.<.ctor>b__1_0(Object unused) at
System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate
callback, Object args, Int32 numArgs) at
System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source,
Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
at System.Windows.Threading.DispatcherOperation.InvokeImpl() at
System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object
state) at
System.Threading.ExecutionContext.RunInternal(ExecutionContext
executionContext, ContextCallback callback, Object state, Boolean

preserveSyncCtx) at
System.Threading.ExecutionContext.Run(ExecutionContext
executionContext, ContextCallback callback, Object state, Boolean
preserveSyncCtx) at
System.Threading.ExecutionContext.Run(ExecutionContext
executionContext, ContextCallback callback, Object state) at
MS.Internal.CulturePreservingExecutionContext.Run(CulturePreservingExecutionContext
executionContext, ContextCallback callback, Object state) at
System.Windows.Threading.DispatcherOperation.Invoke() at
System.Windows.Threading.Dispatcher.ProcessQueue() at

System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32
msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at
MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam,
IntPtr lParam, Boolean& handled) at
MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at
System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate
callback, Object args, Int32 numArgs) at
System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source,
Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
at

System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority
priority, TimeSpan timeout, Delegate method, Object args, Int32
numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd,
Int32 msg, IntPtr wParam, IntPtr lParam) at
MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at
System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame
frame) at
System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
at System.Windows.Application.RunDispatcher(Object ignore) at
System.Windows.Application.RunInternal(Window window) at
System.Windows.Application.Run(Window window) at

System.Windows.Application.Run() at InfoCenter.App.Main() in
D:\Workspace\Visual Studio\MT Info Center WPF\Info
Center\obj\Debug\App.g.cs:line 51

Here is some of the code:

App.xaml

                                   x:Name="App"
                                   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                                   xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                                   xmlns:updater="clr-namespace:InfoCenter.Updater">
    
    

App.xaml.cs:

protected override void OnStartup(StartupEventArgs e)
{
    if (PreProcessor.Prod)
        Dispatcher.UnhandledException += OnDispatcherUnhandledException;

    base.OnStartup(e);

    AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);


    var app = new MainView { ShowInTaskbar = false, Topmost = true }
    var context = new MainViewModel();
    app.DataContext = context;
    app.Show();
}

Other info:
- We deploy using ClickOnce.

- The app have some background tasks that will keep running. It look like it just runs without a view.
- We use MVVM pattern.

If I am missing some information, don't hesitate to ask!

Answer

It was a problem regarding the Culure Info, since you have added this line in your resource file

en-US 

Following this post you should be able to solve your problem uncommenting this line

[assembly: NeutralResourcesLanguage("en-US", UltimateResourceFallbackLocation.Satellite)] 

in your assembly.info.cs