Dekoder html online

Every time a user posts something containing < or > in a page in my web application, I get this exception thrown.

I don't want to go into the discussion about the smartness of throwing an exception or crashing an entire web application because somebody entered a character in a text box, but I am looking for an elegant way to handle this.

Trapping the exception and showing

An error has occurred please go back and re-type your entire form again, but this time please do not use <

doesn't seem professional enough to me.

Disabling post validation (validateRequest="false") will definitely avoid this error, but it will leave the page vulnerable to a number of attacks.

Ideally: When a post back occurs containing HTML restricted characters, that posted value in the Form collection will be automatically HTML encoded.So the .Text property of my text-box will be something & lt; html & gt;

Is there a way I can do this from a handler?

I use the <pre> tag in my blog to post code. I know I have to change < to < and > to >. Are any other characters I need to escape for correct html?

I want to convert & to &, " to " etc.Is there a function in c# that could do that without writing all the options manually?

I found similar questions and answers for Python and Javascript, but not for C# or any other WinRT compatible language.

The reason I think I need it, is because I'm displaying text I get from websites in a Windows 8 store app. E.g. é should become é.

Or is there a better way? I'm not displaying websites or rss feeds, but just a list of websites and their titles.

I am trying to encode special character in html attribute using C# HttpUtility.HtmlEncode.

When I encode this following string

var encode1= HttpUtility.HtmlEncode("Student on  \" On the Rise \"");

the encoding generates the correct output, like this:

Student on  " On the Rise "

The browser encodes the & and again and generate wrong encoding as follow

<meta property="og:title" content="Student on  &amp;quot; On the Rise &amp;quot;" />

How can I tell the browser not to encode the & character again?