title: C# AddMonths() Exception The added or subtracted value results in an un-representable DateTIme
body: <p>I have managed to log an error that points to this code</p>
  <pre><code>DateTime retDate = enddate;
  if (enddate.Day &gt; 1)
  {
      retDate = enddate.AddDays(1 - enddate.Day).AddMonths(1);
  }
  </code></pre>
  <blockquote>
  <p>System.ArgumentOutOfRangeException: The added or subtracted value
  results in an un-representable DateTime.  Parameter name: months<br />
  at System.DateTime.AddMonths(Int32 months)</p>
  </blockquote>
  <p>This was logged in db, but I can not reproduce the issue anymore. I have attempted using every date including a new DateTime() but the if check kicks it out.
  The logic works as desired but I am just trying to find and create a handle for that edge case.</p>