"The workbook is currently open by 256 users" error when opening an Excel workbook from SharePoint or OneDrive

Symptoms

You receive the following error when opening an Excel workbook that is stored on SharePoint or OneDrive:

"The workbook is currently open by 256 users. A maximum of 256 users can have a shared workbook open at the same time.
The workbook will be opened read-only. You can try again later when one or more users have closed the workbook."

Cause

"Shared Workbooks" is a legacy sharing option that allows you to collaborate on a workbook with multiple authors. This feature has been replaced in Microsoft 365 by the co-authoring feature.

Resolution

To resolve this issue, select the Review tab of the ribbon, and within the Protect group select Unshare Workbook.

For other versions of Excel, see the article About the shared workbook feature and follow the steps provided under Additional Information > Turning off the Shared Workbook feature.

More information

For more information about co-authoring, see What you need to co-author.