title: Conversion from UTC to Timezone time produces different result with 4.0 and 3.5 SP1
body: <p>We keep all times in our database as UTC. Based on the client's location the UTC time gets converted to a local time using .net function </p>
  
  <pre><code> public static DateTime ConvertToLocalTime(DateTime utcTime, string timezoneId)
   {
          try
          {
              return TimeZoneInfo.ConvertTimeBySystemTimeZoneId(utcTime, TimeZoneInfo.Utc.StandardName, timezoneId);
          }
          catch
          {
              return new DateTime();
          }
  }
  </code></pre>
  
  <p>There was a problem reported that some reports have produced wrong results in DateTime fields, and when I started looking at it deeper, I realized that the same above code called form SQL2008 (compiled with .net 3.5) produces different result if called from the client application compiled with .net 4.0. The result is incorrect in 3.5 and correct in 4.0 for Chile timezone for year 2015 when DST was observed the whole year. </p>
  
  <p>I can assume that this might have been a missing hotfix specifically produced for .net 3.5 and currently missing. But if anyone previously came across this or similar problem, I would appreciate some extra input.</p>