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WebProxy.UseDefaultCredentials Property

Gets or sets a Boolean value that controls whether the DefaultCredentials are sent with requests.

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

member UseDefaultCredentials : bool with get, set

Property Value

Type: System.Boolean
true if the default credentials are used; otherwise, false. The default value is false.


You attempted to set this property when the Credentials property contains credentials other than the default credentials. For more information, see the Remarks section.

Set this property to true when requests made by this WebProxy object should, if requested by the server, be authenticated using the credentials of the currently logged on user. For client applications, this is the desired behavior in most scenarios. For middle tier applications, such as ASP.NET applications, instead of using this property, you would typically set the Credentials property to the credentials of the client on whose behalf the request is made.

The following table shows the effect of setting the UseDefaultCredentials value, based on the value of the Credentials property.

Credentials value

UseDefaultCredentials value




No effect.



Credentials is set to a null reference (Nothing in Visual Basic).

a null reference (Nothing in Visual Basic)


Credentials is set to DefaultCredentials.

Any value other than DefaultCredentials or a null reference (Nothing in Visual Basic)

true or false

Setting UseDefaultCredentials throws an exception.

If UseDefaultCredentials is false, you can change the Credentials property to any credentials. If UseDefaultCredentials is true, changing the Credentials property from DefaultCredentials (the value that is set when the UseDefaultCredentials property is set to true) will throw an exception.

.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.