OneDrive File Issues

How to Fix Undefined OneDrive Account for Guest SharePoint Users

Camila Milosovich Oct 23, 2026 868 views

Question details

The user needs to resolve an issue where syncing a SharePoint library as a guest user results in an undefined OneDrive account or email address.

Product: OneDrive
Device & OS: not provided
Scenario: Syncing a SharePoint document library from an external organization using a guest B2B account.
Observed behavior: The synced SharePoint libraries display as undefined, and OneDrive prompts for sign-in with an undefined email address. The issue temporarily resolves after restarting but frequently recurs.

Before you start

Ensure you have a stable internet connection and take note of the exact tenant name or URL of the external organization whose SharePoint library you are attempting to sync.

Solution 1Recommended

Reset OneDrive and Re-authenticate the Guest Account

Clearing the local OneDrive sync state and establishing a fresh sign-in session can resolve recurring token authentication glitches.

Often, the connection token between the external SharePoint tenant and your local OneDrive client becomes corrupted or expires, causing the account to appear as 'undefined'. Completely resetting the connection is the most reliable way to refresh these credentials.

Unlink your current account

Click the OneDrive cloud icon in your system tray, go to Help & Settings > Settings > Account, and click 'Unlink this PC'.

Reset the OneDrive client

Press the Windows key + R to open the Run dialog, type '%localappdata%\Microsoft\OneDrive\onedrive.exe /reset', and press Enter.

Sign in with the guest account

Reopen OneDrive and enter the email address you use as a guest for the external organization to complete the sign-in process.

Resync the SharePoint library

Navigate to the external organization's SharePoint library in your web browser and click the 'Sync' button to establish a fresh connection.

Reset OneDrive and Re-authenticate the Guest Account

Solution 2

Verify B2B Sync Policies with Tenant Administrators

External synchronization requires proper authorization. You must verify that neither organization is blocking B2B (Business-to-Business) sync via security policies.

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Frequently Asked Questions

Why does my OneDrive show my guest account as undefined?

This happens when the local OneDrive client loses its authentication token for the external B2B guest session. Without the correct token, OneDrive cannot identify the account name, resulting in the 'undefined' error.

Will restarting my computer fix the undefined SharePoint sync issue?

Restarting the computer and signing back in can force OneDrive to briefly reconnect, which may temporarily fix the issue. However, if the underlying authentication token is corrupted, the problem is likely to return until you fully reset OneDrive.

Can I access external SharePoint files if OneDrive refuses to sync?

Yes. You can bypass the OneDrive local sync application entirely by logging into the external organization's SharePoint site via your web browser to view, edit, and download files directly.

What does it mean if B2B synchronization is blocked by policy?

It means the IT department managing the SharePoint server has implemented security rules (such as Azure AD Conditional Access policies) that prevent non-employees (guests) from downloading or synchronizing company files to their local devices.

Document & File Issues