Runtime: System.TimeZoneInfo.ConvertTimeFromUtc bug

[justlearntutors]

We want to convert time.

Example
Localhost
DateTimeOffset TimeZoneInfoConvert = System.TimeZoneInfo.ConvertTimeFromUtc(DateTime.Parse("10/9/2018 8:00:00 AM"), System.TimeZoneInfo.FindSystemTimeZoneById("W. Europe Standard Time"));

Correct result: 10/9/2018 10:00:00 AM +02:00

Server
DateTimeOffset TimeZoneInfoConvert = System.TimeZoneInfo.ConvertTimeFromUtc(DateTime.Parse("10/9/2018 8:00:00 AM"), System.TimeZoneInfo.FindSystemTimeZoneById("W. Europe Standard Time"));

Wrong result: 10/9/2018 10:00:00 AM +00:00

[sixlettervariables]

ConvertTimeFromUtc returns a DateTime rather than a DateTimeOffset. Given no DateTimeStyles, the parse result will have a kind of Unspecified. The implicit conversion to a DateTimeOffset from a DateTime of kind Local or Unspecified uses your local time zone offset. It seems that your server's time zone is UTC while your local machine's time zone is W. Europe Standard Time. You could confirm that by examining TimeZoneInfo.Local.BaseUtcOffset on both systems.

[Clockwork-Muse]

To be clear, almost certainly what you want to be doing is something similar to:

// Because that date format is culture specific!
var parsedUtc = DateTimeOffset.Parse("2018-10-09 08:00:00", CultureInfo.InvariantCulture);
DateTimeOffset TimeZoneInfoConvert = TimeZoneInfo.ConvertTimeBySystemTimeZoneId(parsedUtc, "W. Europe Standard Time");

...or you can use NodaTime, and use the appropriate domain types.

[tarekgh]

both @sixlettervariables and @Clockwork-Muse are correct. using the way that @Clockwork-Muse suggested will remove the confusion and be explicit.