Calendar Problems

How to Fix Outlook Invitations Saved to the Wrong Calendar

John Wilson Oct 23, 2026 868 views

Question details

The user needs to resolve an issue where accepted calendar invitations in Microsoft Outlook are being saved to a local calendar rather than the primary Microsoft 365 account calendar.

How to Fix Outlook Invitations Saved to the Wrong Calendar

Product: Microsoft Outlook
Device & OS: not provided
Scenario: Accepting calendar invitations while using an IMAP email account alongside a Microsoft 365 account in Outlook.
Observed behavior: Calendar invitations bypass the default Microsoft 365 calendar and are saved to a 'This computer only' calendar, preventing cross-device synchronization.

Before you start

Before proceeding with any data file modifications, ensure that Microsoft Outlook is completely closed. You can verify this by checking your system tray or using the Task Manager to end any running Outlook processes.

Solution 1Recommended

Recreate the IMAP OST Data File

Deleting the local IMAP data file forces Outlook to generate a fresh, uncorrupted version upon the next launch, which typically restores proper calendar routing.

When Outlook uses an IMAP connection, it creates an OST file to cache data locally. If this file becomes corrupted or misconfigured, Outlook may force calendar items into a 'This computer only' folder instead of utilizing your primary Microsoft 365 calendar.

Close Outlook completely

Exit Microsoft Outlook. To be absolutely sure it is not running in the background, press Ctrl + Shift + Esc to open the Task Manager, locate 'Microsoft Outlook', and click 'End task'.

Open the Outlook AppData folder

Press the Windows Key + R on your keyboard to open the Run dialog box. Type `%localappdata%\Microsoft\Outlook` into the text field and press Enter or click OK.

Delete the IMAP OST file

In the File Explorer window that opens, locate the .ost file that corresponds to your IMAP email address. Right-click this file and select 'Delete' (or click the Trash icon in Windows 11).

Restart Outlook and test

Launch Microsoft Outlook again. The application will take a moment to automatically rebuild the deleted OST file from the server. Once synchronized, accept a new calendar invitation to verify it now saves to your default Microsoft 365 calendar.

Safe Data Rebuilding: Deleting an OST file is safe because it is only a local cached copy of your mailbox. Outlook will simply re-download your emails and synchronized data directly from the mail server.

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Frequently Asked Questions

Why do my Outlook calendar items say 'This computer only'?

This tag appears when Outlook is configured with an IMAP account. Because the IMAP protocol only syncs emails and not calendars or contacts, Outlook creates a local-only folder on your specific hard drive to store these items.

Will deleting the OST file delete my saved emails?

No. Deleting the OST file only removes the local cache stored on your computer's hard drive. The next time you open Outlook, it will reconnect to your email server and automatically re-download all your emails.

How do I change my default calendar data file in Outlook?

To change your default data file, click on 'File' in the top ribbon, select 'Account Settings', and click 'Account Settings' again. Go to the 'Data Files' tab, click on the Microsoft 365 data file you wish to use, and click 'Set as Default'.

Outlook & Email Problems