AutoSave OFF / Duplicate File Upload Prompt when editing Excel in SharePoint libraries (Office version 2509/2510)

Hi @Sophie N

I’d like to provide further clarification based on our internal validation:

1. We have already downgraded several clients to version 2508, but the issue persists.
2. The issue affects a wide range of users across departments. Some users may not have reported it yet, but the pattern is widespread.
3. The same behaviour is observed in WORD and PowerPoint, not just Excel.
4. We couldn’t upgrade to build 2511 or later, as those are not yet officially available in any Office update channels.
5. Both OneDrive-synced folders and SharePoint directories exhibit identical symptoms , AutoSave shows “Off,” files cannot be co-authored, and users can’t see who is editing the file.
6. AutoSave is already enabled in the Office application settings (File > Options > Save).
7. The issue affects recently created .xlsx files (not legacy .xls), even simple test files.
8. The problem does NOT occur when opening files from OneDrive/SharePoint via the web interface → “Open in App”, it only occurs when the same file is opened through the locally synced OneDrive folder (via File Explorer). All affected files show a green “Synced” status.

It’s important to note that when AutoSave is left disabled, users can still modify and manually save the file, and those changes sync successfully to OneDrive.

However, the core business impact arises when multiple users open the same file:

• Co-authoring no longer works (no indication of who’s editing).
• Simultaneous edits are lost or forked into duplicates.
• Version control and live collaboration are broken.

Based on this, it seems the regression affects the integration between the Office client and the OneDrive/SharePoint sync interface rather than a single build version.

Could you please:

• Confirm if Microsoft engineering has an active bug ID or internal case tracking this specific regression (for builds 2508–2510)?
• Advise if there is an interim registry, policy, or configuration mitigation that restores AutoSave functionality for synced folders until the fix is released?

Dear @Mahyar Banafsheh,

Thank you for posting your question in the Microsoft Q&A forum reaching out and providing detailed information regarding the AutoSave and duplicate file behavior in Excel when working with SharePoint Online and OneDrive. 

To help me narrow down the cause, could you please provide the following details?  

• Are all users experiencing the same issue or is it specific to specific user accounts? 
• Are you an admin or user of your organization? 
• Have you verified if other file types (like Word or PowerPoint) have similar AutoSave issues? 
• Have you updated to the latest Office build (preferably 2511 or later)? 
• Can you confirm if this issue occurs consistently regardless of whether users access the file via OneDrive sync or directly from SharePoint? 

We understand the inconvenience this issue causes, and we’d like to share the following insights and guidance: 

Microsoft is aware of a regression affecting Office Monthly Enterprise Channel builds 2509 and 2510, where: 

• AutoSave appears OFF for cloud-synced Excel files. 
• Turning AutoSave ON prompts an “Upload” dialog but does not persist. 
• Duplicate files may be created, especially when opening via File Explorer. 

This behavior is inconsistent and linked to how files are opened and handled by the Office client. 

While awaiting a permanent fix, we recommend the following steps: 

1. Open files via Excel > File > Open > OneDrive/SharePoint, rather than File Explorer. 
2. Ensure AutoSave is enabled in Excel settings:  File > Options > Save > “AutoSave files stored in the Cloud by default”. 
3. Avoid using older file formats like .xls; prefer .xlsx. 
4. Save the file manually before enabling AutoSave to avoid duplicate prompts. 

At this time, Microsoft has not officially confirmed resolution in builds 2511 or 2512. We recommend monitoring Release notes for Monthly Enterprise Channel releases - Office release notes | Microsoft Learn for updates. 

If you wish to escalate this issue, please collect: 

• Office and OneDrive version details. 
• Event Viewer logs under Microsoft Office Alerts. 
• Fiddler or HAR logs during file open/save. 
• Screenshots or recordings of the behavior. 

You may also use the Self-help diagnostics for SharePoint Online and OneDrive administrators - SharePoint to assist with troubleshooting. 

I sincerely appreciate your patience and collaboration. Please let me know if you need assistance gathering logs or opening a formal support case. 

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