Can't sync Exchange calendar (eM Client version 7.2.34959.0)

Can’t sync Calendar (EWS) at all. Re-installed eM Client 2 times already and tried “repair” option. No issues with the Outlook and OWA. No issues with the E-mail. Here is the log with the exception:

9:27:28 $** ACC**[Exchange Web Services]  Синхронизация папки '$ ACC /Calendar/’
9:27:43  $
 [Exchange Web Services]  MailClient.Accounts.ConnectionException: Заданный аргумент находится вне диапазона допустимых значений.[a****rgument is out of range]
9:27:43 Имя параметра: dateEnd is earlier than dateStart —> System.ArgumentOutOfRangeException: Заданный аргумент находится вне диапазона допустимых значений. [a****rgument is out of range]
9:27:43 Имя параметра: dateEnd is earlier than dateStart
9:27:43    в System.TimeZoneInfo.AdjustmentRule…ctor(DateTime dateStart, DateTime dateEnd, TimeSpan daylightDelta, TransitionTime daylightTransitionStart, TransitionTime daylightTransitionEnd)
9:27:43    в Microsoft.Exchange.WebServices.Data.TimeZoneTransitionGroup.CreateAdjustmentRule(DateTime startDate, DateTime endDate)
9:27:43    в Microsoft.Exchange.WebServices.Data.TimeZoneDefinition.ToTimeZoneInfo()

Hello Andrey,

This is a problem with a faulty item in the calendar which “ends before it starts”. If you’re able to locate this event, I’d recommend removing it and creating it again.


Hello Russel,

I analyzed almost 500 calendar items for 8 years. In order to do that I used recent Microsoft Exchange WebServices API - I requested properties the way so CreateAdjustmentRule() is triggered. I didn’t find any issues with the broken items and the were no issues with the appointment start/end dates. Then I looked at TimeZoneTransition dates and found out the root cause of the problem which is AdjustmentRule creation procedure. However the problem is not triggered on the recent Microsoft Exchange WebServices API. Further analysis showed that the root cause was fixed in Microsoft Exchange WebServices API back in 2015 when updates were ported from Microsoft codebase. Here is the reference to the particular condition line:

Here is the description for this particular fix:
_ OM:1648848 Due to bad timezone data from clients the startDate may not always come before the effectiveEndDate _

I do not think that I’m the only one experiencing this issue. This issue is critical as EmClient sync process is broken because of the mentioned exception. In my case I had to find the way to remove for about 20 out of 500 appointments for the last 8 years to make EmClient sync process possiblle. Is the any chance this could be fixed in the near future?

P.S.: By the way there are other updates from Microsoft as well. For example, the recent Microsoft Exchange WebServices API supports GetUserPhoto which is a great feature itself.

Thanks in advance,

Hello Andrey,

Thank you for your detailed post. I’ll take a look at it and forward it to our developers for a fix if necessary.



I have been having exactly the same problem for quite some time (currently using eM Client v7.2.36908.0).

@Andrey: Thank you very much for finding out the cause.

@Russel: Are there any planned bug fixes for this in the near future?


Hi, Russel.
I have this issue too. Are you able to fix it?