Troubleshooting Co-Authoring Error "Microsoft Excel cannot access the file..."

Problem:

When working with Excel spreadsheets that contain workbook links, you may run into the following error:

This error happens when some users in an organization have added Box as a Connected Service in Microsoft Office, while others have not.

When users who do not have Box added as a Connected Service within Microsoft Office work with an Excel spreadsheet with workbook links, Excel will attempt to update the workbook links to reflect the local Box Drive path. With Co-Authoring enabled for the organization, Excel appends the local filesystem path to the WOPI URL, creating a broken link.

When users who do have Box added as a Connected Service within Microsoft Office work with the same file, they will encounter this error for the broken link.

Process for Resolution:

To resolve this error, follow the steps outlined below.

1. Ensure that all managed users in your organization are enabled for Box for Microsoft Office Co-Authoring.
   • Admin Console > Integrations > Box for Microsoft Office Co-Authoring
     
2. Ensure that all managed users in your organization have added Box as a Connected Service in Microsoft Office and have signed into their Box accounts.
   • Office App > File > Account > Connected Services
     
3. Have users manually update the broken links.
   • Create Workbook Links 
   • Manage Workbook Links 

Further Reading:

• Guide to enabling coauthoring in Box for Microsoft Office
• Using Microsoft Office Coauthoring Basics