Solution 1: Check Network Connection (VPN/AVD)

Solution 2: Update the Outlook Client version: – Open browser -> Search for “Office.com” -> Install apps -> download M365 Apps exe file -> Install in your system.

Solution 3:- If automatic calendar sync is not working, try to sync the OST manually with Exchange Online. For this,

• Go to Send/Receive tab in Outlook and click the “Update Folder” option. This will sync the calendar and may help to resolve the issue. If it does, check and turn on auto-synchronization. The steps are as follows
• In Outlook 2013 and later versions, navigate to File -> Options -> Advanced. Click the “Send Immediately when connected” checkbox under the “Send and receive “ Section.

• Then click on the “Send/Receive” button and click the “Perform an automatic send/receive” when exiting option.

• Click Close the Outlook Options windows.
• Restart Outlook client for the changes to take effect.