title: Potentially dangerous Request.Form value was detected from the client
body: <p>I am running an ASP.Net MVC application and facing the following error. As I am new to ASP.Net, could someone please help me as to what does it mean and how can I resolve it?</p>
  
  <p>I tried googling to understand it, but found different answers for the same error which left me more confused. </p>
  
  <blockquote>
    <p>Exception caught in Global.asax:System.Web.HttpRequestValidationException (0x80004005): A potentially dangerous Request.Form value was detected from the client (ctl00$MainContent$WarningCtl1$TXTWarningText="
        <p>This is the warni...").
           at System.Web.HttpRequest.ValidateString(String value, String collectionKey, RequestValidationSource requestCollection)
           at System.Web.HttpRequest.ValidateNameValueCollection(NameValueCollection nvc, RequestValidationSource requestCollection)
           at System.Web.HttpRequest.get_Form()
           at System.Web.HttpRequest.get_HasForm()
           at System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull)
           at System.Web.UI.Page.DeterminePostBackMode()
           at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
           at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
           at System.Web.UI.Page.ProcessRequest()
           at System.Web.UI.Page.ProcessRequest(HttpContext context)
           at ASP.app_config_appttypes_groupappttypes_aspx.ProcessRequest(HttpContext context)
           at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
           at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)</p>
  </blockquote>
  
  <p>Please suggest.</p>