XmlWriter.WriteStartDocumentAsync Method (Boolean)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Asynchronously writes the XML declaration with the version "1.0" and the standalone attribute.

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


Public Overridable Function WriteStartDocumentAsync ( _
    standalone As Boolean _
) As Task
public virtual Task WriteStartDocumentAsync(
    bool standalone


  • standalone
    Type: System..::.Boolean
    If true, it writes "standalone=yes"; if false, it writes "standalone=no".

Return Value

Type: System.Threading.Tasks..::.Task
The task that represents the asynchronous WriteStartDocument operation.


Exception Condition

An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message “An asynchronous operation is already in progress.”


An XmlWriter asynchronous method was called without setting the Async flag to true. In this case, InvalidOperationException is thrown with the message “Set XmlWriterSettings.Async to true if you want to use Async Methods.”


This is the asynchronous version of WriteStartDocument(Boolean), with the same functionality. To use this method, you must set the Async flag to true.

Version Information

Windows Phone OS

Supported in: 8.1, 8.0

See Also


XmlWriter Class

WriteStartDocumentAsync Overload

System.Xml Namespace