Outlook on PC is not syncing up with my Outlook on IOS

Check the calendar in Outlook on the web first, because this determines whether Classic Outlook is failing to upload the PC events or Outlook for iOS is failing to display events already stored in Microsoft 365.^1^

1. Isolate where synchronization stops

1. Sign in to Outlook on the web using the same Microsoft 365 account configured in Classic Outlook and on the iPhone.
2. Open Calendar and look for one of the events that currently appears only on the PC.
3. Create a uniquely named test event in Classic Outlook, then check the web calendar again.

Continue with the matching result below.

If the event appears on the web

Microsoft 365 has received the event, so troubleshoot Outlook for iOS:

1. In Outlook for iOS, open Calendar.
2. Tap your avatar or calendar icon in the upper-left corner.
3. Confirm that the calendar belonging to the Microsoft 365 account is listed and checkmarked.
4. Go to Outlook → Settings → Accounts → affected account.
5. Check the account type shown at the top:
   • If it is Microsoft 365/Exchange, tap Reset Account, reopen Outlook, and test.
   • If resetting does not work, select Delete Account → Delete From This Device, and then add the Microsoft 365 account again.
   • If it is IMAP or POP, remove it and add it using the Microsoft 365/Exchange sign-in option. IMAP and POP synchronize email only, not calendars or contacts.^2^

Deleting the account from the device does not delete the server mailbox, but first verify that the events are visible on the web.

If the event does not appear on the web

The PC changes have not reached Microsoft 365. Work through these Classic Outlook checks:

1. Inspect the synchronization log
   • Switch to Folder List view.
   • Expand the mailbox and open Sync Issues.
   • Look for errors created at the time the test event was saved. Record the complete error code and description.
2. Test without add-ins
   • Close Outlook completely.
   • Press Windows key+R, enter:

          outlook.exe /safe
     

   • Create another test event and check Outlook on the web.
   • If it synchronizes, go to File → Options → Add-ins → Manage: COM Add-ins → Go. Disable the add-ins, restart normally, and re-enable them individually to identify the conflict.^3^
3. If Safe Mode does not help, toggle Shared Calendar Improvements
   • Go to File → Account Settings → Account Settings.
   • Double-click the Microsoft 365 account.
   • Select More Settings → Advanced.
   • Toggle Turn on shared calendar improvements to the opposite state.
   • Select Apply → OK, restart Outlook, and test another event.^3^
4. Test in Online Mode
   • Return to File → Account Settings → Account Settings and double-click the account.
   • Clear Use Cached Exchange Mode and restart Outlook.
   • Create a test event and check the web calendar.
   • After the test, re-enable Cached Exchange Mode and restart Outlook.^3^

If events still remain PC-only, contact the Microsoft 365 administrator or Microsoft Support and provide the exact Sync Issues error, whether Safe Mode changed the result, and whether Online Mode uploaded the test event. For a work or school account, Microsoft directs users to their Microsoft 365 administrator or technical support for unresolved Exchange-based synchronization problems.^4^

References

1. Why Outlook app on iphone can not sync with Outlook - Microsoft Q&A
2. [Outlook app](https://support.microsoft.com/outlook/can-t-sync-calendar-and-contacts-with-my-phone-or-tablet)
3. my calendar events are not syncing properly with Exchange Online - Microsoft Q&A
4. Troubleshoot Outlook mobile issues | Microsoft Support