title: SignalR: There was an error invoking Hub method "XXX"
body: <p>Server:</p>
  
  <pre><code>public void AddLine(string line)
  {
      Clients.Others.addLine(line);
  }
  </code></pre>
  
  <p>.NET Client:</p>
  
  <pre><code>await rtHubProxy.Invoke("AddLine", "lineInfo");
  </code></pre>
  
  <p>Exception:</p>
  
  <pre><code>InvalidOperationException: There was an error invoking Hub method 'xxx.AddLine'.
  </code></pre>
  
  <p>Actually, I was trying to invoke the method with complex object, only to find the exception. Therefore, I changed the type of the parameter and left the AddLine() body blank for debugging purposes, which weirdly enough, it still threw the same exception.</p>
  
  <p>I also have another SignalR invocation on the client-side, just several lines above, which runs responsively without error. The corresponding server-side code as follows:</p>
  
  <pre><code>public void Hello(string text)
  {
      Clients.All.hello(text);
  }
  </code></pre>
  
  <p>Could anyone find out where I've got wrong? I've been debugging for more than 4 hours and still cannot find the undoing even after I simplified the code.</p>
  
  <p>(Spelling strictly checked, no mismatch.)</p>