title: HttpContext.Current.Cache item null after page refresh
body: <p>I've a C# web page in which I'm storing a List&lt;> object in the server cache, using HttpContext.Current.Cache. The object is saved in the cache after the first page load. When I refresh the page though, the cache object is null. Any thoughts?</p>
  
  <p>Also, I'd like to set up a "job" to recreate the object every 30 minutes. I'd like to serve up the cached version until the new one is created, and then replace the old with the new.
  How do I do that?</p>
  
  <p>In my Global.asax, in Application_Start, I've got the following:</p>
  
  <pre><code>HttpRuntime.Cache.Insert("MainADList", Uf.GetUsers(), null, Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(30));
  </code></pre>
  
  <p>When I need it, I do the following:</p>
  
  <pre><code> MainADList = (Users)HttpRuntime.Cache["MainADList"];
  </code></pre>
  
  <p>Which is for the most part null. Not always, but almost always.</p>