title: ASP.NET web server cannot be launched and Mono environment not be switched
body: <p>I am running <a href="http://software.opensuse.org/download/package?project=home:tpokorra:mono&amp;package=monodevelop-opt" rel="noreferrer">one of the latest versions of Monodevelop</a> on Linux Mint which used to work before I formatted my drive and made a fresh install. When I build my project it builds fine, but when I try to run it I get the following message:</p>
  
  <blockquote>
    <p>Could not launch ASP.NET web server.
    The xsp4 web server cannot be found. Please ensure that it is installed.</p>
  </blockquote>
  
  <p>I have xsp4 and xsp4-base packages installed. I found <a href="https://askubuntu.com/questions/360841/monodevelop-doesnt-find-xsp4-web-server-although-it-is-installed-running">in a question and answer on askubuntu</a> that I need to switch the Mono runtime to make it able to find xsp4.</p>
  
  <p>When I go to Edit > Preferences > Projects > .NET Runtimes I see the options <code>Mono 3.10.0 (Default)</code> and <code>Mono 3.10.0 (/usr)</code>. Unfortunately, when I switch to the <code>/usr</code> one (the one I need and should work) I get the same error as above that the web server cannot be found. And now the weird part: when I look again in the .NET runtimes options I see that is has switched the default back to the original one.</p>
  
  <p><img src="https://i.stack.imgur.com/BqvKv.png" alt="The problem visualised."></p>
  
  <p>The switching back to another default only happens after I press F5 and try to build the solution (both with release and debug).</p>
  
  <p>Does anyone know how I can fix this?</p>