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title description ms.date dev_langs
System.TypeInitializationException class
Learn about the System.TypeInitializationException class.
12/31/2023
CSharp
VB
FSharp

System.TypeInitializationException class

[!INCLUDE context]

When a class initializer fails to initialize a type, a xref:System.TypeInitializationException is created and passed a reference to the exception thrown by the type's class initializer. The xref:System.Exception.InnerException property of xref:System.TypeInitializationException holds the underlying exception.

Typically, the xref:System.TypeInitializationException exception reflects a catastrophic condition (the runtime is unable to instantiate a type) that prevents an application from continuing. Most commonly, the xref:System.TypeInitializationException is thrown in response to some change in the executing environment of the application. Consequently, other than possibly for troubleshooting debug code, the exception should not be handled in a try/catch block. Instead, the cause of the exception should be investigated and eliminated.

xref:System.TypeInitializationException uses the HRESULT COR_E_TYPEINITIALIZATION, which has the value 0x80131534.

For a list of initial property values for an instance of xref:System.TypeInitializationException, see the xref:System.TypeInitializationException.%23ctor%2A constructors.

The following sections describe some of the situations in which a xref:System.TypeInitializationException exception is thrown.

Static constructors

A static constructor, if one exists, is called automatically by the runtime before creating a new instance of a type. Static constructors can be explicitly defined by a developer. If a static constructor is not explicitly defined, compilers automatically create one to initialize any static (in C# or F#) or Shared (in Visual Basic) members of the type. For more information on static constructors, see Static Constructors.

Most commonly, a xref:System.TypeInitializationException exception is thrown when a static constructor is unable to instantiate a type. The xref:System.Exception.InnerException property indicates why the static constructor was unable to instantiate the type. Some of the more common causes of a xref:System.TypeInitializationException exception are:

  • An unhandled exception in a static constructor

    If an exception is thrown in a static constructor, that exception is wrapped in a xref:System.TypeInitializationException exception, and the type cannot be instantiated.

    What often makes this exception difficult to troubleshoot is that static constructors are not always explicitly defined in source code. A static constructor exists in a type if:

    • It has been explicitly defined as a member of a type.

    • The type has static (in C# or F#) or Shared (in Visual Basic) variables that are declared and initialized in a single statement. In this case, the language compiler generates a static constructor for the type. You can inspect it by using a utility such as IL Disassembler. For instance, when the C# and VB compilers compile the following example, they generate the IL for a static constructor that is similar to this:

    .method private specialname rtspecialname static
        void  .cctor() cil managed
{
  // Code size       12 (0xc)
  .maxstack  8
  IL_0000:  ldc.i4.3
  IL_0001:  newobj     instance void TestClass::.ctor(int32)
  IL_0006:  stsfld     class TestClass Example::test
  IL_000b:  ret
} // end of method Example::.cctor

    The following example shows a xref:System.TypeInitializationException exception thrown by a compiler-generated static constructor. The Example class includes a static (in C#) or Shared (in Visual Basic) field of type TestClass that is instantiated by passing a value of 3 to its class constructor. That value, however, is illegal; only values of 0 or 1 are permitted. As a result, the TestClass class constructor throws an xref:System.ArgumentOutOfRangeException. Since this exception is not handled, it is wrapped in a xref:System.TypeInitializationException exception.

    :::code language="csharp" source="./snippets/System/TypeInitializationException/Overview/csharp/ctorException1.cs" id="Snippet3"::: :::code language="vb" source="./snippets/System/TypeInitializationException/Overview/vb/CtorException1.vb" id="Snippet3":::

    Note that the exception message displays information about the xref:System.Exception.InnerException property.

  • A missing assembly or data file

    A common cause of a xref:System.TypeInitializationException exception is that an assembly or data file that was present in an application's development and test environments is missing from its runtime environment. For example, you can compile the following example to an assembly named Missing1a.dll by using this command-line syntax:

    csc -t:library Missing1a.cs
    fsc --target:library Missing1a.fs
    vbc Missing1a.vb -t:library

    :::code language="csharp" source="./snippets/System/TypeInitializationException/Overview/csharp/Missing1a.cs" id="Snippet1"::: :::code language="fsharp" source="./snippets/System/TypeInitializationException/Overview/fsharp/Missing1a.fs" id="Snippet1"::: :::code language="vb" source="./snippets/System/TypeInitializationException/Overview/vb/Missing1a.vb" id="Snippet1":::

    You can then compile the following example to an executable named Missing1.exe by including a reference to Missing1a.dll:

    csc Missing1.cs /r:Missing1a.dll
    vbc Missing1.vb /r:Missing1a.dll

    However, if you rename, move, or delete Missing1a.dll and run the example, it throws a xref:System.TypeInitializationException exception and displays the output shown in the example. Note that the exception message includes information about the xref:System.Exception.InnerException property. In this case, the inner exception is a xref:System.IO.FileNotFoundException that is thrown because the runtime cannot find the dependent assembly.

    :::code language="csharp" source="./snippets/System/TypeInitializationException/Overview/csharp/Missing1.cs" id="Snippet2"::: :::code language="fsharp" source="./snippets/System/TypeInitializationException/Overview/fsharp/Missing1.fs" id="Snippet2"::: :::code language="vb" source="./snippets/System/TypeInitializationException/Overview/vb/Missing1.vb" id="Snippet2":::

    [!NOTE] In this example, a xref:System.TypeInitializationException exception was thrown because an assembly could not be loaded. The exception can also be thrown if a static constructor attempts to open a data file, such as a configuration file, an XML file, or a file containing serialized data, that it cannot find.

Regular expression match timeout values

You can set the default timeout value for a regular expression pattern matching operation on a per-application domain basis. The timeout is defined by a specifying a xref:System.TimeSpan value for the "REGEX_DEFAULT_MATCH_TIMEOUT" property to the xref:System.AppDomain.SetData%2A?displayProperty=nameWithType method. The time interval must be a valid xref:System.TimeSpan object that is greater than zero and less than approximately 24 days. If these requirements are not met, the attempt to set the default timeout value throws an xref:System.ArgumentOutOfRangeException, which in turn is wrapped in a xref:System.TypeInitializationException exception.

The following example shows the xref:System.TypeInitializationException that is thrown when the value assigned to the "REGEX_DEFAULT_MATCH_TIMEOUT" property is invalid. To eliminate the exception, set the"REGEX_DEFAULT_MATCH_TIMEOUT" property to a xref:System.TimeSpan value that is greater than zero and less than approximately 24 days.

:::code language="csharp" source="./snippets/System/TypeInitializationException/Overview/csharp/Regex1.cs" id="Snippet4"::: :::code language="fsharp" source="./snippets/System/TypeInitializationException/Overview/fsharp/Regex1.fs" id="Snippet4"::: :::code language="vb" source="./snippets/System/TypeInitializationException/Overview/vb/Regex1.vb" id="Snippet4":::

Calendars and cultural data

If you attempt to instantiate a calendar but the runtime is unable to instantiate the xref:System.Globalization.CultureInfo object that corresponds to that calendar, it throws a xref:System.TypeInitializationException exception. This exception can be thrown by the following calendar class constructors:

  • The parameterless constructor of the xref:System.Globalization.JapaneseCalendar class.
  • The parameterless constructor of the xref:System.Globalization.KoreanCalendar class.
  • The parameterless constructor of the xref:System.Globalization.TaiwanCalendar class.

Since cultural data for these cultures should be available on all systems, you should rarely, if ever, encounter this exception.