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RegistryKey.OpenSubKey Method (String, RegistryKeyPermissionCheck, RegistryRights)

Retrieves the specified subkey for read or read/write access, requesting the specified access rights.

Namespace:  Microsoft.Win32
Assembly:  mscorlib (in mscorlib.dll)

member OpenSubKey : 
        name:string * 
        permissionCheck:RegistryKeyPermissionCheck * 
        rights:RegistryRights -> RegistryKey 


Type: System.String
The name or path of the subkey to create or open.
Type: Microsoft.Win32.RegistryKeyPermissionCheck
One of the enumeration values that specifies whether the key is opened for read or read/write access.
Type: System.Security.AccessControl.RegistryRights
A bitwise combination of enumeration values that specifies the desired security access.

Return Value

Type: Microsoft.Win32.RegistryKey
The subkey requested, or a null reference (Nothing in Visual Basic) if the operation failed.


name is a null reference (Nothing in Visual Basic)


permissionCheck contains an invalid value.


The RegistryKey is closed (closed keys cannot be accessed).


rights includes invalid registry rights values.


The user does not have the requested permissions.

Rather than throwing an exception, this method returns a null reference (Nothing in Visual Basic) if the requested key does not exist.

If permissionCheck is RegistryKeyPermissionCheck.ReadWriteSubTree, the key is opened for reading and writing; if permissionCheck is RegistryKeyPermissionCheck.ReadSubTree or RegistryKeyPermissionCheck.Default, the key is opened for reading unless the parent key was opened with RegistryKeyPermissionCheck.ReadWriteSubTree.

The access specified for permissionCheck takes precedence over the access specified for rights. For example, if you specify RegistryKeyPermissionCheck.ReadSubTree for permissionCheck and RegistryRights.WriteKey for rights, an attempt to write to the subkey throws an exception.

In order to use the OpenSubKey method, you must have an instance of the RegistryKey class. To get an instance of RegistryKey, use one of the static members of the Registry class.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.