Outlook calendar not syncing

Summary

This guide helps you troubleshoot and resolve: Outlook calendar not syncing. Follow the steps below to fix the issue.

Common Causes

This article outlines troubleshooting steps for Outlook calendar events not syncing between desktop and mobile devices in Microsoft 365. Common causes include cached mode corruption, connectivity issues, and incorrect account configuration. Follow these steps to restore calendar synchronisation across your devices.

Quick Fix Steps

1. Restart Outlook on your desktop computer.
2. Restart the Outlook app on your mobile device.
3. Check your internet connection on both devices.
4. Sign out of your Microsoft 365 account in Outlook, then sign back in.

Detailed Instructions

Check Outlook Online

1. Open a web browser and go to outlook.office.com.
2. Sign in with your Microsoft 365 email address and password.
3. Select the Calendar icon from the left-hand navigation pane.
4. Verify that your calendar events appear correctly.

If your events are missing in Outlook Online, the issue is with your Microsoft 365 account rather than the Outlook application. If events appear online but not on your desktop or mobile device, proceed to the next steps.

Check Microsoft 365 Service Health

Visit the Microsoft 365 Service Health dashboard to confirm there are no known Outlook or calendar service disruptions affecting your organisation.

Update the Outlook App

1. On your mobile device, open the App Store (iOS) or Google Play Store (Android).
2. Search for Microsoft Outlook.
3. If an update is available, tap Update.
4. On your desktop, open Outlook, select File > Office Account > Update Options > Update Now.

Remove and Re-add Your Account

1. In Outlook desktop, select File > Account Settings > Account Settings.
2. Select your email account and click Remove.
3. Confirm the removal when prompted.
4. Click New and follow the prompts to add your email account again.
5. Restart Outlook and check if calendar events begin syncing.

Disable Cached Exchange Mode

1. In Outlook desktop, select File > Account Settings > Account Settings.
2. Select your Microsoft 365 account and click Change.
3. Under Offline Settings, clear the checkbox for Use Cached Exchange Mode.
4. Click Next, then Finish.
5. Restart Outlook and test calendar synchronisation.
6. If syncing works, you may re-enable Cached Exchange Mode using the same steps to restore offline access.

Check Shared and Delegate Calendars

If you are syncing shared or delegate calendars, ensure you have the correct permissions and that the calendar owner has shared the calendar with you. Shared calendars may not sync to mobile devices unless added through the Outlook app's "Add Shared Calendar" option.

Troubleshooting

Mobile Device Sync Issues

• Ensure the Outlook app has permission to access your calendar in your device settings.
• Check that Background App Refresh is enabled for Outlook on iOS, or that background data is unrestricted on Android.
• Remove the Outlook app from your mobile device and reinstall it from the App Store or Google Play Store.
• Confirm you are using the same Microsoft 365 account on both desktop and mobile.

Desktop Sync Issues

• Select Send / Receive > Send/Receive All Folders or press F9 to force a manual synchronisation.
• Check that your computer's date and time are set correctly.
• Temporarily disable any third-party antivirus or firewall software to test if it is blocking Outlook's connection to Microsoft 365.
• Review the Sync Issues folder in your Outlook folder list for specific error messages.

If calendar synchronisation issues continue after following these steps, please Open a Ticket and our support team will assist you further.

If you host with us, you don't need to do this yourself — just Open a Ticket and our Brisbane team will get it sorted.

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