UploadStringAsync Method (Uri, String)

WebClient.UploadStringAsync Method (Uri, String)


Uploads the specified string to the specified resource. This method does not block the calling thread.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public void UploadStringAsync(
	Uri address,
	string data


Type: System.Uri

The URI of the resource to receive the string. For HTTP resources, this URI must identify a resource that can accept a request sent with the POST method, such as a script or ASP page.

Type: System.String

The string to be uploaded.

Exception Condition

data is null.


The address parameter is null.


The data parameter is null.


The URI formed by combining BaseAddress and address is invalid.


There was no response from the server hosting the resource.

This method sends a string to a resource. The string is sent asynchronously using thread resources that are automatically allocated from the thread pool. Before uploading the string, this method converts it to a Byte array using the encoding specified in the Encoding property. To receive notification when the string upload completes, you can add an event handler to the UploadStringCompleted event.

This method does not block the calling thread while the string is being sent. To send a string and block while waiting for the server's response, use one of the UploadString 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 in the .NET Framework.

.NET Framework
Available since 2.0
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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