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Hello Guys I have a problem I used this line:

DateTime DateUTCKin1 = (new DateTime()).AddMilliseconds(TimeKin1);

To convert my "TimeKin1" which is in milisecond and is equal to 1664459293023, it is suposed to be 29 sept 2022 13:48 but the result of this line is 29 sept 0053 13:48. So it is not the right year and i don't know why. Do you ? Thank you for your answers

What I have tried:

My "TimeKin1" is in long like the methods asks. I've tried others method to convert my milisecond into UTC but this one seems to me the easier and more logical one.
Updated 26-Oct-22 22:16pm

Your "milliseconds" value is obviously relative to a base date/time.

By subtracting the milliseconds from the known value it is supposed to represent, we can find that base value:
DateTime baseDate = new DateTime(2022, 9, 29, 13, 48, 0, 0, DateTimeKind.Utc).AddMilliseconds(-1664459293023);
// 31/12/1969 23:59:46
That seems like an odd choice, so I'm assuming you've simply missed out 13 seconds from your expected value. That would leave you with a base date of 1970-01-01T00:00:00Z, which is the Unix epoch[^].

You will need to use that value in your calculations:
private static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

public static DateTime ConvertMillisecondsToTime(long milliseconds)
    return UnixEpoch.AddMilliseconds(milliseconds);
That will give you:
DateTime DateUTCKin1 = ConvertMillisecondsToTime(TimeKin1);
// 2022-09-29T13:48:13Z

NB: If the milliseconds actually represent the "Unix time", then you could use the DateTimeOffset.FromUnixTimeMilliseconds[^] method instead, which would give you a DateTimeOffset value:
DateTimeOffset DateUTCKin1 = DateTimeOffset.FromUnixTimeMilliseconds(TimeKin1);
// 2022-09-29T13:48:13Z
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OriginalGriff 27-Oct-22 4:03am    
Member 15802708 27-Oct-22 4:09am    
AH yhea you're right I used an online convert to see if the time was right and it was a unix epoch converter so it gives me the right time, thank you very much !
Your value is incorrect, 29/09/2022 13:48 is 62135596786977 in milliseconds.
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