How to fix “Upload Blocked” and “Sign in required” for OneDrive/SharePoint files.

The alerts "Upload Blocked: We couldn't verify you have the necessary permissions to upload the file" and "Sign in required: We need your credentials to upload your changes" occur when Microsoft Office’s local authentication tokens fall out of sync with Microsoft 365, OneDrive, or SharePoint. When this happens, local edits become trapped in the local Microsoft Office Document Cache. Excel cannot commit changes to the cloud even though your internet connection is active and your account appears signed in.

Quick Answer

Do not close Excel immediately. First, click File > Save As and save a copy locally to your Desktop to prevent data loss. Next, close all Office apps, open the Windows Start menu, search for Credential Manager, click Windows Credentials, and delete all entries under Generic Credentials that start with MicrosoftOffice16_Data. Reopen Excel and sign in again.

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Step 1: Secure Your Local Changes

When an upload is blocked, your changes exist only in your computer’s temporary memory and local cache. If you close Excel before backing up, those modifications may be discarded.

1. Press F12 (or click File > Save As).
2. Choose a local folder, such as your Desktop or C:\Temp\.
3. Save the file under a distinct name (e.g., Financials_Local_Backup.xlsx).
4. Keep this file safe while you clear the authentication conflict.

If your local drive also rejects the save due to system permissions, follow “Document not saved”: Troubleshooting permission and disk space issues.

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Step 2: Clear Expired Office Credentials in Windows

The most common cause of persistent “Sign in required” loops is an expired or corrupted OAuth authentication token stored in Windows Credential Manager.

1. Close all open Microsoft Office applications (Excel, Word, PowerPoint, Outlook, Teams).
2. Click the Windows Start button, type Credential Manager, and press Enter.
3. Select the Windows Credentials tab.
4. Scroll down to the Generic Credentials section.
5. Look for entries matching these patterns:
   • MicrosoftOffice16_Data:...
   • MS.Identity...
   • OneDrive Cached Credential
6. Click the arrow next to each matching entry and select Remove.

Windows Credentials Manager
└── Generic Credentials
    ├── MicrosoftOffice16_Data:live:cid=...  ──► [Remove]
    ├── MicrosoftOffice16_Data:org.freedesk...──► [Remove]
    └── MS.Identity.Universal:...            ──► [Remove]

1. Restart your computer.
2. Open Excel. Click Sign In in the top-right corner and enter your Microsoft 365 credentials.

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Step 3: Resolve Multiple Account Identity Collisions

If you use a personal Microsoft account (e.g., Outlook.com) alongside a work or school account (corporate Azure AD / Entra ID) on the same machine, Excel can send the wrong authentication token to SharePoint.

How to Check for Identity Collisions:

1. Open Excel and click File > Account.
2. Under User Information, verify which account is actively connected.
3. Review the Connected Services section below your account details.
4. If you see personal OneDrive accounts mixed with corporate SharePoint tenants, click Remove on the unneeded services.
5. Click Switch Account or sign out completely, then sign back in using the specific account that has permission to access the target SharePoint library.

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Step 4: Clear the Local Office Document Cache

If credentials are valid but the “Upload Blocked” banner persists, the cached version of the file inside the local Office Document Cache has desynchronized from the version stored in the cloud.

1. Open Excel and navigate to File > Options.
2. Click the Save category in the left sidebar.
3. Scroll down to Cache Settings.
4. Check the box marked Delete files from the Office Document Cache when they are closed.
5. Click the Delete cached files button.

Excel Options > Save > Cache Settings
├─────────────────────────────────────────────────────────────┤
| [✔] Delete files from the Office Document Cache when closed  |
|                                                             |
| [ Delete cached files ] ◄────────────────────────────────── |
+─────────────────────────────────────────────────────────────+

1. Confirm the prompt and restart Excel.

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Step 5: Adjust OneDrive Co-Authoring Sync Settings

If the file is synced via the OneDrive desktop application, a conflict between OneDrive’s file handler and Excel’s co-authoring engine can freeze upload queues.

1. Click the OneDrive cloud icon in your Windows taskbar notification area (near the system clock).
2. Click the Gear icon (Settings) > Settings.
3. Go to the Advanced settings section (or the Office tab in older OneDrive clients).
4. Locate the setting: Use Office applications to sync Office files that I open.
5. Toggle this setting Off, wait 10 seconds, and toggle it back On.

This resets the integration handshake between the local OneDrive sync engine and the desktop Office client.

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Diagnostic Step 6: Identify Sync Conflicts

If another user edited the same section of the workbook while your computer was offline or experiencing network drops, Excel may block your upload because it cannot automatically merge the changes.

If this happens, Excel displays a secondary prompt asking you to resolve the conflicting changes. To troubleshoot this specific state, review “Merge Conflict”: Resolving co-authoring errors in Excel Online.

If your changes repeatedly fail to upload because the AutoSave feature turns itself off without warning, proceed to Troubleshooting “AutoSave” being disabled automatically.