title: Error messages stored in SESSION
body: <p>Is it a good practice to store error messages in <code>SESSION</code>? For example after a redirect. Passing in through url isnt a solution for me...
  I am wondering if it is a good solution... because..</p>
  
  <p>Would a concurent submit of user cause problem? (A long time-taking post, while ajax content is obtained from another tab) that may mess up the session! Or that is impossible to happen?</p>
  
  <p>If user makes a request and it fails for some reason to display the page then the message may be shown at an irrelevant page!</p>
  
  <p>So? Any alternatives??<br>
  For example when using POST/redirected/get pattern</p>