How do i get rid of __o is not declared?

I’ve found the answer on the .net forums. It contains a good explanation of why ASP.Net is acting the way it is:

We have finally obtained reliable repro and identified the underlying issue. A trivial repro looks like this:

  <% if (true) { %>

  <%=1%>
  <% } %>
  <%=2%>   

In order to provide intellisense in <%= %> blocks at design time, ASP.NET generates assignment to a temporary __o variable and language (VB or C#) then provide the intellisense for the variable. That is done when page compiler sees the first <%= … %> block. But here, the block is inside the if, so after the if closes, the variable goes out of scope. We end up generating something like this:

   if (true) { 
        object @__o;
        @__o = 1;
   }
   @__o = 2;

The workaround is to add a dummy expression early in the page. E.g. <%=”” %>. This will not render anything, and it will make sure that __o is declared top level in the Render method, before any potential ‘if’ (or other scoping) statement.

An alternative solution is to simply use

<% response.write(var) %>

instead of

<%= var %>