Outlook Favorite Folders and Calendar Groups not syncing from Exchange Online

Copper Contributor


One of our colleagues got a new PC and his Favorites and Calendar Groups are not properly synced from Exchange Online in Outlook 2016.

  • "Favorites" only contains "Sent Items" - and not his five other custom folders
  • "Calendar Groups" are only partially populated - with some Groups containing no Calendars - and others containing one or few calendars.

We have tried:

  • Creating a new Outlook Profile
  • Running Outlook in Online Mode, instead of Cached Mode
  • Removing Profile.ost file
  • Removing Outlook.xml file
  • Emptying RoamCache folder

Unfortunately none of this helps.


It definitely seems to be an issue locally on the new PC

  • When accessing Outlook.Office.com all folders and Calendars are present
  • When adding a new Calendar/Group in Outlook.Office.com it appears on new PC
  • If the User logs on to another PC with fresh User Profile all favorites appear

Starting Outlook with /ResetNavpane switch might solve the issue - but would also wipe out his (many) custom Groups and Calendars.


Does anyone know of a way to reset local NavPane settings and load from Online?
Preferably without resetting Online settings or creating new User Profile on PC.

Best regards

11 Replies

All of our users are having the same issue, started with a few users on Jan 4, now every user is affected by the next day.  You can add stuff and it will sync to the server, but it will not sync back down to other users.  You can see the added items in OWA, but not on the local PC outlook app.  I also contacted a 3rd party IT support company to help, since I did all the fixes you listed and some with nothing fixing the issue.  After talking with the company, they too were having customers with the same issues.  Looks to me it's server side related and not the local machine.  We had to temporarily put all users to not cache public folders and turned off Cached Exchange mode.  It's a workaround, but it's EXTREMLY SLOW working in Outlook for all users.  I hope this issue is fixed soon.




I have this same issue and it started this week.  Problematic computers stopped synchronizing on 12/29 and they throw sync errors after recreating the favorite and recreating the profile.  The initial download is good, but subsequent changes fail to sync.  This is what we get in the sync error:


8:30:27 Uploading to server 'https://outlook.office365.com/mapi/emsmdb/?MailboxId='blahblah'

8:30:27 Error synchronizing folder

8:30:27                    [80004005-501-80004005-230]

8:30:27                    The client operation failed.

8:30:27                    Microsoft Exchange Information Store





Thank your for your replies @BenHendricksWC and @spookytay 
Although I had hoped for an easy fix, it is nice to hear that we are not the only ones experiencing the issue. :)

May I ask what Outlook Desktop versions you are using at your organizations?
We are currently on Outlook 2016 (no 365 clients yet) - and I wonder if it might be a client compatibility issue?

Anyway I may end up opening a case with Microsoft, based on your feedback.
Will post results if anything usable comes from it.

Best regards



We are using current version of Outlook Version 2112 (Build 14729.20194 Click-to-Run) Current Channel



@MartinHolstDk @BenHendricksWC 


Here's what I did and so far and it's working.  I tried this fix before, but I didn't wait it out long enough for it to work, kept thinking Outlook froze after 20 minutes, and I would kill the process.


Here's what I did.

  1. I had all users turn "Cached Exchange Mode" back on, and under "Cached Exchange Mode Setting" made sure all the check boxes were checked. 
  2. I also turned off "Shared Calendar Improvements"  (not sure if this step is necessary, but I did it just to make sure)
  3. Restart Outlook, then go to your public calendar properties, click on the Synchronization tab and check the "Statistics for this folder"  Make a note of the last sync date, mine was Jan 4, 7 days ago)
  4. Click on the General tab, and click "Clear Offline items" (This is where I didn't wait long enough)
  5. Wait for the process to finish, it will freeze windows, and look like Outlook is frozen, but it's not. Depending on the size of the calendar will determine how long it takes, I had to do two calendars, one took about 35 minutes and the other only 10), Even if the window comes up that it's finished and Outlook is still frozen, keep waiting, it's not done yet, but will be eventually. 
  6. Once Outlook is finished and it's unfrozen, you can restart Outlook
  7. Go back to the public calendar properties, click on the synchronization tab, and check the last sync date, it should be current and you should be good to go at this point.  

If you have more than one public calendar like I do, just repeat the steps for each one.  I also turned "Shared Calendar Improvements" back on for each user.  So far I've only tested minimal, but we can post something to the calendar and it will sync up with all the other users now.




I have local group policies as well as O365 policies that make cache mode changes difficult for my current handful of users that noticed the issue.  All are running the latest O365 Outlook...


Another thread (Synchronization issue - Microsoft Community) appears to have finally received some attention with a reply from MS Agent/Moderator that they will investigate further.







It may still work for you.  I had turn off "cached exchange mode" for all my users as a temporary work around to get things synced across all users.  I had to turn it back on to do the fix.  If your users have it enable, which I assume they do, it may still work.  Just skip the step of turning it back on.

Well that didn't last long. All users are starting to get the issue again. Fix only worked for about 8 hours it looks like.


We have the same issue, also started on De3cember 29th.

Using the shared folder instead of thew favorites is not speedy enough when working over the internet, and sear5ches take a huge time.

I have been having this issue with a customer who use public folders for capturing certain incoming and outgoing emails (two separate folders) for the previous 6 months.
This issue stared at the very end of last year for them where the public folder favourites would suddenly stop syncing new emails.
We have done some troubleshooting and it seems that the folders sync ok until an email in one of these folders is marked as read, then it stops syncing immediately.
I can replicate this issue off site with different accounts.
Looking forward to somebody finding a fix for this as we can't keep removing the cache and favourites and then re-adding them due to Outlook killing their devices while it catches up again.

Sorry for having been absent from the thread...

My original issue was only with shared calendars (meeting rooms, colleagues etc.) that users had added as favorites.

In conclusion it seems that there was an issue in late 2021, which broke sync with existing favorites from Exchange Online to Outlook Desktop Client.

However newly created Calendar "Favorites" seem to sync OK.
So the only workaround for us is currently to reset favorites (Outlook.exe /ResetNavpane) - and then recreate favorite lists.

EDIT: ...and now I see that the issue has also been reported "fixed" in the other thread previously mentioned... :)
Synchronization issue - Microsoft Community

Best regards