I have an issue on some users with Outlook 2019, which Calendar won't sync updates on meeting.

Outlook is connected to Microsoft Exchange 2016 On-prem.

So, meeting was created by User A, and User B and User C accepted meeting. They got update on their Calendar, and now they have meeting time set for 18:00PM-18:30PM. User A who created meeting changed time on the meeting to 18:30PM-19:00PM, he got update of the time, but problematic User B and User C doesn't, and their time is still showing 18:00PM-18:30PM.

In Sync Issues folder, there is log:

Synchronizer Version 16.0.13628

Synchronizing Mailbox 'User B'

Synchronizing server changes in folder 'Calendar'

Downloading from server 'https://exchange16.contoso.com/mapi/emsmdb/?MailboxId=xxxx'

120 item(s) added to offline folder

Could not connect to public folder server.


The attempt to log on to Microsoft Exchange has failed.

Microsoft Exchange Information Store

For more information on this failure, click the URL below:



I have done restart of the Outlook, restart of the PC, did Quick repair, did Online repair, also deleted mailbox and added it again but no prevail.

Does anyone have suggestion where to look next ?

#Edit1: Important to add is that Webex meeting invitation was included. #Edit2: Get-MessageTrackingLog

I will divide picture in 4 parts:
1st: User A creates an update for the calendar and send update to users.
2nd: User B received update, but actual update is not shown on Calendar on client end.
3rd: User A didn't do any action, but log shows he send some update to users.
4th: User B received update on Calendar client, but time which he received was from previous update, and it's wrong.

2 Answers 2


Have you checked if the calendar updated in OWA? How many users are affected? How often do these issue happen?

If calendar sync well in OWA, this issue may be related with outlook client, you could run outlook in safe mode and check if there are some add-ins causing this issue. In addition, You may try the Calendar Checking Tool (CalCheck) to help troubleshoot the issue: Information about the Calendar Checking Tool for Outlook (CalCheck)

  • Now shows correct time for the meeting, it updated over the night. I now don't know what was the issue. I forgot to mention one important thing, that regarding this meeting, it had Webex meeting invitation in it. I know that it happened on two users. Didn't happened before. Regarding OWA, it didn't updated there, I have checked. I tried CalCheck, but app didn't worked, but I tried at the end of my working time, so I didn't investigated why this app didn't run. Like I said, now it shows correct time. When I tried to recreate the issue, I didn't tried with Webex invitation included.
    – Pathfinder
    Feb 9, 2021 at 11:51
  • I guess that calendar need more time to sync when you add Webex invitation in it.
    – Joy Zhang
    Feb 11, 2021 at 6:23
  • Today I'm experiencing the same problem, yesterday, date has been pushed for some days ahead, but internal recipients today received an update which set time from an old update. Is there a way how can I confirm which time is sent over the update, and which time external recipients received ?
    – Pathfinder
    Feb 11, 2021 at 8:35
  • Or, since the Cisco Webex Productivity Tools is included (Webex Meetings), can I somehow confirm that this is not issue on my end (my domain, Outlook, Exchange Server)?
    – Pathfinder
    Feb 11, 2021 at 9:34

You could run get-messagetrackinglog to check the time of calendar updating. enter image description here

In addition, i'm not familiar with Cisco Webex Productivity Tools, could you disable it then check if this issue perists?

  • I have updated original post, in #Edit2 you can see output I get from Get-MessageTrackingLog.
    – Pathfinder
    Feb 12, 2021 at 12:30
  • Event ID DELIVER indicates that A message was delivered to a local mailbox. in other words, the time of calendar updating is the time of message delivered in mailbox. for more details: docs.microsoft.com/en-us/exchange/mail-flow/transport-logs/… From your test screenshots, there seems no issue in server but in outlook calendar sync. I still suspect that this problem is related to Cisco Webex Productivity Tools.
    – Joy Zhang
    Feb 15, 2021 at 6:30

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