title: Sys.WebForms.PageRequestManagerServerErrorException / HTTP1.1 Internal Server Error
body: <p>I've perused the forums for a couple weeks now trying out different solutions, but nothing seems to be helping. Here's my problem:</p>
  
  <p>I have created an ASP.NET Web Application for displaying dashboard-style metrics in a Service Desk setting. The client has large screens in the service desk room that display specific pages of my web app. </p>
  
  <p>Some pages use UpdatePanel, others use $.ajax to make calls to code behind every 15 seconds (I have various [WebMethod]'s set up for the ajax calls). </p>
  
  <p>These dashboards work fantastic for about a day, maybe 2, then they stop refreshing, and the above error message can be found in the console. Bug checking for the ajax methods show they hit the 'error:' portion of the ajax call. </p>
  
  <p>Below are solutions I have tried to no avail:</p>
  
  <p>Added <code>EnableSessionState="False"</code> to the <code>&lt;%@ Page %&gt;</code> header. </p>
  
  <p>Added <code>validateRequest="false"</code> to the <code>&lt;%@ Page %&gt;</code> header.</p>
  
  <p>Added <code>enableEventValidation="false"</code> to the <code>&lt;%@ Page %&gt;</code> header. </p>
  
  <p>Added try-catch statements to my web methods to catch the error.</p>
  
  <p>Added Global.asax and overrode the Application_Error. Made it write to an application event log. Example below.</p>
  
  <pre><code>Exception exc = Server.GetLastError().GetBaseException();
          if (!EventLog.SourceExists("Dashboards"))
          {
              EventLog.CreateEventSource("Dashboards", "Dashboard");
          }
  
          EventLog log = new EventLog();
          log.Source = "Dashboards";
          log.WriteEntry(exc.ToString());
  
          Server.ClearError();
  </code></pre>
  
  <p>This Global.asax exception is never called (as far as I can tell) and I never have any exceptions logged. </p>
  
  <p>I can't think of any other troubleshooting to do with this.</p>
  
  <p>If I had to guess, I would say it's the every 15 second ajax/updatepanel calls that is causing the issue. The app is running on IIS v8 on Server 2012. Perhaps IIS thinks it's getting DDOS'd or something similar? Another possibility is that I have various threads running in the code behind (aspx.cs) updating information that the ajax call then pulls from. Maybe the thread is getting killed somehow?</p>
  
  <p>I am currently out of ideas. Any help with troubleshooting would be appreciated. I'm more than happy to upload more code as example as well.</p>
  
  <p>Thank you to anyone who can assist with this.</p>