Why Word Co-authoring Returns ‘Upload Failed’ on Specific Document Types

When multiple users try to edit a Word document simultaneously, the co-authoring feature allows real-time collaboration. Some document types trigger an “Upload Failed” error during co-authoring, preventing any user from saving changes. This error occurs because Word enforces specific file format and storage requirements for co-authoring to function correctly. This article explains why certain document types cause the upload failure and provides steps to convert or reconfigure those files for successful co-authoring.

Why Word Co-authoring Fails on Specific Document Types

Word co-authoring depends on the file being in a compatible format and stored in a supported location. The feature uses a synchronization engine that requires the document to be saved as a .docx file on OneDrive, SharePoint, or Microsoft 365 Groups. When a document uses an older format like .doc, .dot, .docm, or .dotx, the co-authoring engine cannot lock the file for simultaneous edits. The “Upload Failed” error is Word’s way of telling you that the file cannot be synced because it does not meet the technical requirements for real-time collaboration.

Incompatible File Formats

The .docx format is the only Word format that supports co-authoring. Older binary formats (.doc, .dot) and macro-enabled formats (.docm, .dotm) are not compatible. The co-authoring protocol relies on metadata and file-locking mechanisms that only exist in the Open XML format (.docx). If you attempt to co-author a .doc file saved on OneDrive, Word will attempt to convert it, but the upload may fail if the conversion process encounters any corruption or permission issues.

Unsupported Storage Locations

Co-authoring only works when the document is stored on OneDrive, SharePoint, or within a Microsoft 365 Group. Documents saved on a local hard drive, network share, or third-party cloud service like Dropbox or Google Drive cannot be co-authored. Word will show the “Upload Failed” error because the file cannot be synced through the Microsoft synchronization engine. Even if the file is saved on OneDrive but accessed through a mapped network drive, co-authoring will fail.

Restricted Permissions and Macros

Documents with Information Rights Management (IRM) permissions or ActiveX controls often block co-authoring. IRM restricts who can edit the file, and the co-authoring engine cannot negotiate permissions between multiple users simultaneously. Similarly, documents containing macros (.docm) are blocked because macros can modify the document structure in ways that conflict with concurrent editing. Word disables co-authoring on these files to prevent data corruption.

Steps to Convert and Reconfigure Documents for Co-authoring

To resolve the “Upload Failed” error, convert your document to the .docx format and ensure it is stored in a supported location. Follow these steps to prepare a document for co-authoring.

1. Save the document as .docx format
   Open the document in Word. Go to File > Save As. In the “Save as type” dropdown, select “Word Document (.docx)”. Click Save. If the document contains macros, Word will warn you that macros will be removed. Confirm the action. This step ensures the file uses the Open XML format required for co-authoring.
2. Move the file to OneDrive or SharePoint
   In File Explorer, locate the converted .docx file. Right-click the file and select Copy. Navigate to your OneDrive folder or a SharePoint document library. Right-click and select Paste. Alternatively, use the File > Save As dialog in Word and choose OneDrive or SharePoint as the location.
3. Remove restricted permissions
   Open the document in Word. Go to File > Info > Protect Document. If you see “Restricted Access” listed, click on it and select “Unrestricted Access.” If you are not the permission owner, ask the file owner to remove IRM restrictions. Without this step, co-authoring will still fail.
4. Disable ActiveX controls
   Go to File > Options > Trust Center > Trust Center Settings > ActiveX Settings. Select “Disable all controls without notification.” Click OK twice. Then save the document again. ActiveX controls are often embedded in legacy forms and block co-authoring.
5. Share the file with collaborators
   Open the document from OneDrive or SharePoint. Click the Share button in the top-right corner of Word. Enter the email addresses of your collaborators and set their permission level to “Can edit.” Click Send. Collaborators will receive a link to the document and can begin co-authoring.

If the Document Still Shows “Upload Failed”

After converting and moving the file, close Word completely and reopen the document from the OneDrive or SharePoint location. Try making a small edit and saving. If the error persists, check your internet connection and ensure your Microsoft 365 subscription is active. Co-authoring requires a stable internet connection and a valid license for all users.

If Word Still Has Issues After the Main Fix

Upload Failed on a .docx File Stored on OneDrive

Even a .docx file can fail to upload if the file is larger than 100 MB or contains embedded media like videos or high-resolution images. OneDrive has a file size limit of 250 MB for syncing, but co-authoring performance degrades significantly above 100 MB. Reduce the file size by compressing images: select an image, go to Picture Format > Compress Pictures, and choose “Email (96 ppi).” Save the document and try co-authoring again.

Upload Failed in a SharePoint Document Library With Custom Metadata

SharePoint libraries that require custom metadata columns can cause upload failures during co-authoring. When a user saves a document, SharePoint demands that required metadata fields be filled. If the metadata form does not appear correctly, the upload fails. To fix this, ask the SharePoint administrator to set the metadata columns as optional instead of required. Alternatively, fill in all required metadata fields before sharing the document for co-authoring.

Upload Failed When Using the Word Web App

The Word Web App (Word for the web) has stricter file format restrictions than the desktop version. It only supports .docx files and does not support .doc or .dot files at all. If you open an older format in Word for the web, it will attempt a conversion but may fail silently. Always use the desktop version of Word to convert the file first, then open it in the web app for co-authoring.

Item	Co-authoring Supported	Upload Failure Likely
File format .docx	Yes	No, if stored correctly
File format .doc	No	Yes
File format .dotx	No	Yes
File format .docm	No	Yes
Storage on OneDrive	Yes	No, if file is .docx
Storage on SharePoint	Yes	No, if file is .docx
Storage on local drive	No	Yes
IRM restricted	No	Yes
Contains macros	No	Yes
File size over 100 MB	Possible	Yes, performance degrades

You can now convert any incompatible document to .docx, move it to OneDrive or SharePoint, and remove permissions or macros to enable co-authoring. Try sharing a test .docx file with one collaborator to verify the fix. For ongoing collaboration, use the AutoSave toggle in Word to ensure all changes are synced in real time. If you frequently work with macro-enabled documents, consider saving a macro-free copy specifically for co-authoring sessions.