System.Resources.MissingManifestResourceException class

This article provides supplementary remarks to the reference documentation for this API.

A MissingManifestResourceException exception is thrown for different reasons in .NET versus UWP apps.

.NET apps

In .NET apps, MissingManifestResourceException is thrown when the attempt to retrieve a resource fails because the resource set for the neutral culture could not be loaded from a particular assembly. Although the exception is thrown when you try to retrieve a particular resource, it is caused by the failure to load the resource set rather than the failure to find the resource.

Note

For additional information, see the "Handling a MissingManifestResourceException Exception" section in the ResourceManager class topic.

The main causes of the exception include the following:

• The resource set is not identified by its fully qualified name. For example, if the baseName parameter in the call to the ResourceManager.ResourceManager(String, Assembly) method specifies the root name of the resource set without a namespace, but the resource set is assigned a namespace when it is stored in its assembly, the call to the ResourceManager.GetString method throws this exception.

  If you've embedded the .resources file that contains the default culture's resources in your executable and your app is throwing a MissingManifestResourceException, you can use a reflection tool such as the IL Disassembler (Ildasm.exe) to determine the fully qualified name of the resource. In ILDasm, double click the executable's MANIFEST label to open the MANIFEST window. Resources appear as .mresource items and are listed after external assembly references and custom assembly-level attributes. You can also compile the following simple utility, which lists the fully qualified names of embedded resources in the assembly whose name is passed to it as a command-line parameter.

  using System;
  using System.IO;
  using System.Reflection;
  
  public class Example0
  {
     public static void Main()
     {
        if (Environment.GetCommandLineArgs().Length == 1) { 
           Console.WriteLine("No filename.");
           return;
        }
        
        string filename = Environment.GetCommandLineArgs()[1].Trim();
        // Check whether the file exists.
        if (! File.Exists(filename)) {
           Console.WriteLine("{0} does not exist.", filename);
           return;
        }   
        
        // Try to load the assembly.
        Assembly assem = Assembly.LoadFrom(filename);
        Console.WriteLine("File: {0}", filename);
           
        // Enumerate the resource files.
        string[] resNames = assem.GetManifestResourceNames();
        if (resNames.Length == 0)
           Console.WriteLine("   No resources found.");
  
        foreach (var resName in resNames)
           Console.WriteLine("   Resource: {0}", resName.Replace(".resources", ""));
  
        Console.WriteLine();
     }
  }
  

  Imports System.IO
  Imports System.Reflection
  Imports System.Resources
  
  Module Example3
      Public Sub Main()
          If Environment.GetCommandLineArgs.Length = 1 Then
              Console.WriteLine("No filename.")
              Exit Sub
          End If
          Dim filename As String = Environment.GetCommandLineArgs(1).Trim()
          ' Check whether the file exists.
          If Not File.Exists(filename) Then
              Console.WriteLine("{0} does not exist.", filename)
              Exit Sub
          End If
  
          ' Try to load the assembly.
          Dim assem As Assembly = Assembly.LoadFrom(filename)
          Console.WriteLine("File: {0}", filename)
  
          ' Enumerate the resource files.
          Dim resNames() As String = assem.GetManifestResourceNames()
          If resNames.Length = 0 Then
              Console.WriteLine("   No resources found.")
          End If
          For Each resName In resNames
              Console.WriteLine("   Resource: {0}", resName.Replace(".resources", ""))
          Next
          Console.WriteLine()
      End Sub
  End Module
  

• You identify the resource set by its resource file name (along with its optional namespace) and its file extension rather than by its namespace and root file name alone. For example, this exception is thrown if the neutral culture's resource set is named GlobalResources and you supply a value of GlobalResources.resources (instead of GlobalResources) to the baseName parameter of the ResourceManager.ResourceManager(String, Assembly) constructor.

• The culture-specific resource set that is identified in a method call cannot be found, and the fallback resource set cannot be loaded. For example, if you create satellite assemblies for the English (United States) and Russia (Russian) cultures but you fail to provide a resource set for the neutral culture, this exception is thrown if your app's current culture is English (United Kingdom).

MissingManifestResourceException uses the HRESULT COR_E_MISSINGMANIFESTRESOURCE, which has the value 0x80131532.

MissingManifestResourceException uses the default Equals implementation, which supports reference equality.

For a list of initial property values for an instance of MissingManifestResourceException, see the MissingManifestResourceException constructors.

Note

We recommend that you include a neutral set of resources in your main assembly, so your app won't fail if a satellite assembly is unavailable.

Universal Windows Platform (UWP) apps

UWP apps deploy resources for multiple cultures, including the neutral culture, in a single package resource index (.pri) file. As a result, in a UWP app, if resources for the preferred culture cannot be found, the MissingManifestResourceException is thrown under either of the following conditions:

• The app does not include a .pri file, or the .pri file could not be opened.
• The app's .pri file does not contain a resource set for the given root name.