UploadFileTaskAsync Method (String, String, String)

WebClient::UploadFileTaskAsync Method (String^, String^, String^)

.NET Framework 4.6 and 4.5

Uploads the specified local file to a resource as an asynchronous operation using a task object.

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

[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)]
Task<array<unsigned char>^>^ UploadFileTaskAsync(
	String^ address,
	String^ method,
	String^ fileName


Type: System::String^

The URI of the resource to receive the file. 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 method used to send the data to the resource. If null, the default is POST for http and STOR for ftp.

Type: System::String^

The local file to send to the resource.

Return Value

Type: System.Threading.Tasks::Task<array<Byte>^>^

Returns Task<TResult>.

The task object representing the asynchronous operation. The Result property on the task object returns a Byte array containing the body of the response received from the resource when the file was uploaded.

Exception Condition

The address parameter is null.


The fileName parameter is null.


The URI formed by combining BaseAddress and address is invalid.


fileName is null, is Empty, contains invalid character, or the specified path to the file does not exist.


An error occurred while opening the stream.


There was no response from the server hosting the resource.


The Content-type header begins with multipart.

This operation will not block. The returned Task<TResult> object will complete after the file has been uploaded to the resource. The file is sent asynchronously using thread resources that are automatically allocated from the thread pool.

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

If the BaseAddress property is not an empty string (""), 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.

BY default, 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 4.5
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