ASP.NET: Problem with summernote form

Hi, I have a very simple data modification form with one field.
I converted it to a summernote, from that moment if I change the text on a line there is no problem.
As soon as I try to move to new line, it no longer saves me the text. Why?

Animation1108×434 267 KB

Seems like it not accept HTML tag
In browser debug I have this error:

[HttpRequestValidationException (0x80004005): Valore potenzialmente pericoloso Request.Form rilevato dal client (testo="<p>aaas asd as asdas...").]
   System.Web.HttpRequest.ValidateString(String value, String collectionKey, RequestValidationSource requestCollection) +417
   System.Web.HttpRequest.ValidateHttpValueCollection(HttpValueCollection collection, RequestValidationSource requestCollection) +279
   System.Web.HttpRequest.get_Form() +59
   System.Web.HttpRequest.get_HasForm() +80
   System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull) +49
   System.Web.UI.Page.DeterminePostBackMode() +111
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +10218
   System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +348
   System.Web.UI.Page.ProcessRequest() +75
   System.Web.UI.Page.ProcessRequest(HttpContext context) +105
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +872
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +220
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +94