title: Invalid postback or callback argument.Event validation is enabled using
body: <p>Since moving to .net 4.5.1 from 2.0 I have this error</p>
  <blockquote>
  <p>Invalid postback or callback argument.  Event validation is enabled using  in configuration or &lt;%@ Page EnableEventValidation=&quot;true&quot; %&gt; in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.  If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.</p>
  <p>[ArgumentException: Invalid postback or callback argument.  Event validation is enabled using  in configuration or &lt;%@ Page EnableEventValidation=&quot;true&quot; %&gt; in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.  If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.]<br />
  System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument) +144<br />
  System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument) +111<br />
  System.Web.UI.WebControls.DropDownList.LoadPostData(String postDataKey, NameValueCollection postCollection) +55<br />
  System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) +16<br />
  System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad) +303<br />
  System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1593</p>
  </blockquote>
  <p>What I can do?</p>
  <p>I have this problem on localhost, but if I try to acces it remote the problem is solved (on another workstation). If the workmate try to acces it on his pc ( the one that work for me) they encounter the same problem but if they use my workstation the app works.</p>