HttpListenerResponse.AddHeader Method

Note: This method is new in the .NET Framework version 2.0.

Adds the specified header and value to the HTTP headers for this response.

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

public void AddHeader (
	string name,
	string value
public void AddHeader (
	String name, 
	String value
public function AddHeader (
	name : String, 
	value : String



The name of the HTTP header to set.


The value for the name header.

Exception typeCondition


name is a null reference (Nothing in Visual Basic) or an empty string ("").


You are not allowed to specify a value for the specified header.


name or value contains invalid characters.


The length of value is greater than 65,535 characters.

Calling this method is equivalent to calling the Set method on the collection returned by the Headers property.

If the header specified in name does not exist, this method inserts a new header into the Headers property's collection. If name is present in the collection, this method replaces the existing value with value. To add a value to an existing header without replacing the existing value, use the AppendHeader method.

The following code example demonstrates adding a header using this property.

public static void SetExpirationDate(long seconds, HttpListenerResponse response)
    response.AddHeader("Expires", seconds.ToString());

Windows 98, Windows Server 2003, Windows XP Media Center Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0

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