WebClient.UploadDataAsync Method (Uri, Byte[])

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

Uploads a data buffer to a resource identified by a URI, using the POST method. This method does not block the calling thread.

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

Public Sub UploadDataAsync ( _
	address As Uri, _
	data As Byte() _
Dim instance As WebClient
Dim address As Uri
Dim data As Byte()

instance.UploadDataAsync(address, data)
public void UploadDataAsync (
	Uri address, 
	byte[] data
public function UploadDataAsync (
	address : Uri, 
	data : byte[]



The URI of the resource to receive the data.


The data buffer to send to the resource.

Exception typeCondition


The URI formed by combining BaseAddress and address is invalid.


An error occurred while opening the stream.


There was no response from the server hosting the resource.

This method sends a data buffer to a resource. The data buffer is sent asynchronously using thread resources that are automatically allocated from the thread pool. The data is not encoded. To receive notification when the data upload completes, add an event handler to the UploadDataCompleted event.

This method does not block the calling thread while the data is being sent. To send data and block while waiting for the server's response, use one of the UploadData methods.

Asynchronous operations that have not completed can be canceled using the CancelAsync method.

If the BaseAddress property is not an empty string (""), and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the STOR command to upload an FTP resource. For an HTTP resource, the POST method is used.


This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 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