User Mailbox migrated to EXO, still no calendar in Teams

Occasional Contributor

All the research I've done has shown that while the organization is in Hybrid mode with Exchange 2013 on-prem, the on-prem mailbox users will not be able to access the Calendar and some other functions in Teams. It also shows that once we migrate said user's mailbox to Exchange Online (assuming proper licensing) that the functionality should appear. I have observed that it can take days (up to 4) for this to happen and provide the user full functionality. I've ran a case on this and support has not been helpful. Has anyone else encountered this? 


The calendar is still missing in Teams after migrating to O365.

9 Replies

@MattShafer Hey, as far as I know you need Exchange 2016 CU3+ (with sync to Azure AD & OAuth configuration required).


*edit* realized I read your post a bit too fast as you've migrated to EXO already.


@PeterRising Hello friend! Something you've stumbled across during your migrations to EXO?

Hi @MattShafer 


As @ChristianBergstrom says, if mailboxes are on Exchange On-Prem, then there is some work to be done, but once migrated to Exchange Online, the calendar option should become available.  


How long has it been now since you migrated the mailbox to Exchange Online please?



We had a test account that experienced this first. We had moved the test account up to EXO, and had full teams functionality immediately. Testing functionality, we moved it back to our on-prem servers to confirm we could do it (business req); then moved it back up to EXO successfully. After this migration it took 4 full calendar days to appear, during which time I ran the mentioned support case. Support closed it claiming something I did in troubleshooting resolved the issue. 


Yesterday I migrated my account as the first LIVE user account to move from on-prem to EXO. Nearly 24 hours later, almost to the minute, from my migration it has appeared without warning. I migrated another user later in the day yesterday. That user's migration ended up completing around midnight last night. They still do not have the calendar, but do have other EXO integrated apps like To-do. Hopefully when they log in tomorrow morning, they will have the calendar.


 It's a bit anticlimactic considering this is one of the key features users will be looking for (that we're missing on EX2013). I'm really looking to see if there's any PowerShell cmdlet or script I can run to help make this more consistent. 

best response confirmed by MattShafer (Occasional Contributor)



Frustrating I agree, but I think as things stand all you can do is wait I'm afraid.  Not aware of anything that would speed up the process.

@PeterRising Thanks Peter! As far as I know all should be good when using EXO but just had to ask for a second opinion. Appreciate your reply (as always). @MattShafer Hopefully it's nothing else than waiting for it to populate then. Cheers!

@MattShafer Sounds like a delay (something synchronising in the background) and that users should see the calendar in Teams after 24 hours. If you download the log files for Teams (CTRL+Shift+Alt+1) you should see that EnableCalendarApp is set to true when Teams know that there is an calendar.


You could also try the web client for Teams, sometimes it updates faster.


And for next time, we are always recommending doing migrations and larger changes on Friday afternoon since there is almost always a up to 24 hours (or more) delay in Teams/Cloud services.

Yeah as Linus said check the web teams client and see if it’s there. It’s likely just signing out of teams and back in could force it to check to load the calendar tab. Restarting computer and Teams isn’t quiet the same as a sign out and in but something else to try to try and force it to be quicker as it should not take that long to update if your migration is complete.

Another thing when you do your migrations in exchange side you are completing them once it’s done migrating I assume?

@Chris Webb and @Linus Cansby 


Thanks for your responses. The synchronization in the background, and not-so-instant nature of O365, is understood. The issue I have is the inconsistency with the timeline. Some users are instant, others take 24 hours, others have taken multiple (so far as many as 5) days. My first test user was instantaneous, but that has not held true for any subsequent migrations even with the same account. I really hope I don't need to tell my ~600 users that after migration they may need to wait up to a week, or not at all, for something as simple as calendar access to be granted. I have to say I'm a bit shocked by everyone's position that this is acceptable.


As for troubleshooting, we have attempted all of the following to move it along without success. This indicates to me it's a backend issue. 

  • close and reopen application
  • sign out and sign in
  • reinstall of Teams on PC (system wide installer)
  • We have also investigated MDM as a possible contributor, and have ruled it out


I hear your point about it being enabled on the client. However, the behavior is the same across all access methods (PC, web, native iOS). This is "the big feature" that really makes Teams shine for them post migration because there is so much integration between EXO and Teams. It's very frustrating that Microsoft can't make it reasonably consistent. In many companies, a frustrating initial experience can be a death stroke for an application before it even gets started, and that is my fear here. We are already combating the, "Why do we need Teams when we have Skype" people. This will be my users first experience with Microsoft 365 as a SaaS app. We have deployed the CTR apps for years with on-prem services. Also, sometimes a Friday night migration is not appropriate as not all businesses stop for the weekend, or have a consistent 5-day 8-5 M-F work week. 


In answer to the specific question about completing the batch, yes they are being completed manually, so far within an hour of the initial sync completing.


I appreciate the responses. 



Hey guys,


we're currently facing this exact same issue(/behavior) while migrating a customer's exchange to the cloud.

We're using Exchange 2013 OnPrem, which of course doesn't support the Teams calendar integration. After migrating our first test user to exchange online, the calendar feature became available almost instantly.

We then migrated a few other "pilot" users and were then seeing the mentioned problems. Calendar integration is not available for somewhere between 1 and 7 days, until it finally appears in the user's Teams client (desktop aswell as browser).


The "Microsoft Teams Calendar Tab Test" also shows no issues directly after migrating the mailbox.


For our customer's IT it's hard to speak to their management and tell them "We're migrating now, maybe sometime next week the calendar will be available, but we won't know for sure".