NullReferenceException Class

The exception that is thrown when there is an attempt to dereference a null object reference.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

public class NullReferenceException : SystemException
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public class NullReferenceException extends SystemException
public class NullReferenceException extends SystemException
Not applicable.

Note that applications throw the ArgumentNullException exception rather than the NullReferenceException exception discussed here.

The following Microsoft intermediate language (MSIL) instructions throw NullReferenceException :

  • callvirt

  • cpblk

  • cpobj

  • initblk

  • ldelem.<type>

  • ldelema

  • ldfld

  • ldflda

  • ldind.<type>

  • ldlen

  • stelem.<type>

  • stfld

  • stind.<type>

  • throw

  • unbox

NullReferenceException uses the HRESULT COR_E_NULLREFERENCE, which has the value 0x80004003.

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


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0