Message in Japanese (日本語)
この WebSocket インスタンスには未処理の '<var>X</var>' 呼び出しが既に 1 つあります。ReceiveAsync と SendAsync は同時に呼び出すことができますが、それぞれに許可される未処理の操作は同時に 1 つまでです。
Unlocalized message
There is already one outstanding '<var>X</var>' call for this WebSocket instance. ReceiveAsync and SendAsync can be called simultaneously, but at most one outstanding operation for each of them is allowed at the same time.
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