Email Sync Problems

How to Fix Outlook Files Not Syncing After OneDrive Backup

Tauseeq Magsi Sep 30, 2026 870 views

Question details

The user is unable to access BigPond emails and Outlook folders after a OneDrive or Windows backup, with data files failing to sync due to 'in use' errors.

How to Fix Outlook Files Not Syncing After OneDrive Backup

Product: Microsoft Outlook and OneDrive
Device & OS: Windows
Scenario: A Windows or OneDrive backup was initiated, causing active Outlook data files to be uploaded to a synchronized cloud folder.
Observed behavior: Outlook data files fail to synchronize with OneDrive because they are reported as 'in use'. Re-adding the email account or switching to the new Outlook results in missing account folders.

Before you start

Ensure that Microsoft Outlook is completely closed before attempting to move or modify any data files, as running the application will lock the files and prevent you from making changes.

Solution 1Recommended

Move Active Outlook Data Files Out of OneDrive

Active Outlook data files (.pst or .ost) cannot sync properly while in use. Moving them to a local, non-synced folder resolves the synchronization conflict.

Microsoft OneDrive is not designed to synchronize active Outlook data files. When Outlook is open, it continuously locks these files, which causes OneDrive to report an 'in use' error and halt the sync process.

Close Microsoft Outlook

Exit Microsoft Outlook completely to release any system locks on your email data files.

Locate Synced Files

Open File Explorer and navigate to your OneDrive folder where the Outlook files (.pst or .ost) are currently being stored.

Move to a Local Folder

Cut the Outlook data files and paste them into a local directory that is not synced with OneDrive, such as C:\Users\[YourUsername]\Documents\Outlook Files.

Update Outlook Settings

Open Outlook, go to File > Account Settings > Account Settings. Select the Data Files tab, click on your account, and update the file location to point to the new local folder you just created.

Move Active Outlook Data Files Out of OneDrive

Sync Restored: Once the files are moved outside the OneDrive directory, OneDrive will stop attempting to sync them, clearing the 'in use' error messages.

Solution 2

Restore Account Folders via Control Panel

If re-adding the account caused missing folders, you need to ensure Outlook is loading the correct original data file rather than generating a new, empty profile.

Free Microsoft Office alternative

Switch to WPS Office for a Hassle-Free Experience

Tired of complex synchronization conflicts and heavy resource usage in Microsoft Office? Try WPS Office. It provides a lightweight, fast, and completely free alternative for your daily document productivity needs without forcing unwanted cloud backups.

1. Download the Installer: Visit the official WPS Office website to download the free, lightweight installer.
2. Install the Suite: Run the installation file and follow the on-screen prompts to complete the setup in minutes.
3. Start Creating: Open WPS Office and start creating, editing, or viewing your Microsoft Office compatible documents immediately.

Fully compatible with Microsoft Word, Excel, and PowerPoint formats.Lightweight installation that won't bog down your system or interfere with local files.Familiar and intuitive tabbed interface for a seamless transition.Built-in PDF editing capabilities included at no extra cost.

Frequently Asked Questions

Why does OneDrive say my Outlook files are 'in use'?

Outlook continuously locks its active data files (.pst and .ost) while the application is running. OneDrive cannot safely synchronize these files while they are locked, resulting in the 'in use' error.

Does Windows Backup automatically save my Outlook emails?

No, Windows Backup and OneDrive do not natively back up active Outlook data files. If your files were synced, it usually means your default document save location was redirected to a OneDrive folder during setup.

How do I recover folders lost when switching to the 'New Outlook'?

If you switched to the 'New Outlook' and lost folders, it may have failed to import your old local data file. Reverting to classic Outlook or manually importing your original .pst file via the Account Settings menu can restore your missing folders.

Outlook & Email Problems