Excel AutoSave and Sync Failure in SharePoint Libraries After Check Out - Version 2509+ Issue

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Excel AutoSave and Sync Failure in SharePoint Libraries After Check Out - Version 2509+ Issue

Stefan Velciu 20

I have SharePoint libraries configured to open documents in the desktop application and to allow editing only after performing a Check Out. Therefore, when an Excel file is opened, it opens in Read-Only mode and prompts for Check Out. After performing the Check Out, AutoSave is activated and the document switches to edit mode.

Up to this point, everything works normally. However, after making changes to the document and after a random amount of time, the file loses synchronization and AutoSave is disabled. As a result, the original file in the SharePoint library remains locked (Checked Out), and the one in the application must be saved as a new file.

In these conditions, many users have lost their work in the files, which is frustrating. It is important that in these SharePoint libraries, users cannot edit files simultaneously and that there is only one version — that’s why Check Out is enabled by default. Also, files should not be edited in the browser but in the desktop application, because some of them are XLSM files. However, I want to emphasize again that this issue also occurs with regular files (XLSX).

The issue occurs randomly for some users as the Excel application from Microsoft 365 Apps for enterprise was updated from version 2508 to 2509. This problem still persists in the current version (2510).Issue report with screenshots.pdf

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Answer 1

Hi @Stefan Velciu,

Welcome to Microsoft Q&A.

First of all, thank you sincerely for taking the time to report this issue in such a clear and detailed manner, and for attaching the supporting documentation. Your thorough explanation has been incredibly helpful in understanding the scope and impact of the problem.

From what you've described, this appears to be a critical issue affecting AutoSave and synchronization between Excel and SharePoint when using the Check Out feature. The fact that this behavior began with version 2509 of Microsoft 365 Apps and continues in 2510 suggests a potential regression or compatibility issue introduced in recent updates.

Given the severity and the potential for data loss, I recommend the following steps:

1. Report the Issue to Microsoft Support

Since this appears to be a version-specific issue, your Microsoft 365 administrator should open a support ticket via the Microsoft 365 Admin Center. The backend support team can:

Analyze tenant-level logs.
Investigate Excel sync and AutoSave behavior.
Identify any service-side bugs or policy conflicts.
Provide hotfixes or rollback guidance if applicable.

When submitting the ticket, please include:

A detailed description (as you've provided here).
The affected Office versions (2509, 2510).
Screenshots or logs (from your attached report).
Confirmation that the issue occurs across multiple users.

2. Temporary Workarounds to Minimize Impact

While awaiting a permanent fix, here are some practical steps to help reduce disruption:

Rollback to Office version 2508, where the issue was not observed.

Guide: Change update channels or roll back Office versions

Encourage users to save frequently, especially after Check Out.

Even with AutoSave enabled, manual saves can help preserve progress.

Monitor AutoSave status: Ask users to keep an eye on the AutoSave toggle in Excel. If it turns off unexpectedly, save the file immediately to avoid data loss.
Admin monitoring: IT admins should regularly check for locked files in SharePoint and assist users in unlocking or restoring versions when needed.
Enable version history in SharePoint libraries to help recover lost work if needed.

Thank you again for your detailed report. I truly hope this issue is resolved soon so your team can return to a smooth and reliable workflow. If you run into any issues while trying the steps, or if something still doesn’t feel quite right, please don’t hesitate to reach out again. I’ll do my best to support you however I can.

Looking forward to hearing back from you with any updates or additional details.

Warm regards,

Liora

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Liora D 18,915 Reputation points Microsoft External Staff Moderator

2025-10-23T15:08:15.9633333+00:00

Hi @Stefan Velciu,

I just wanted to follow up to see how things are going with the information I shared above. I truly hope it was helpful and brought you closer to resolving the issue.

If you’ve had a chance to review it and have any updates, questions, or if you ran into any difficulties along the way, please don’t hesitate to let me know. I’m more than happy to assist further if needed.

It would be great to hear back from you!

Warm regards,

Liora.
Liora D 18,915 Reputation points Microsoft External Staff Moderator

2025-10-26T16:02:05.2766667+00:00

Hi @Stefan Velciu,

Just checking in one last time to see if you still need any assistance with this topic. I completely understand that things can get busy, so no worries at all if you haven’t had a chance to respond yet.

If the information shared earlier helped resolve your issue, feel free to click "Accept Answer" to help others with similar questions. Otherwise, I’m still here and happy to support you whenever you're ready.

If you have any other questions in the future, please don’t hesitate to create a new thread, myself and other moderators are always ready to help. We truly hope you have a smooth experience with Microsoft products and wish you continued success in your work.

Best regards,

Liora.