Microsoft has resolved the Office Online issues (https://status.office.com/) and we are considering the issue resolved.
If you are still experiencing issues previewing or opening files on Box using Office Online or the Excel Online Previewer, please reach out to us at https://support.box.com.
Our testing and customer reports indicate most users are now able to successfully preview and open files on Box using the Excel Online Previewer and Office Online integrations.
We are continuing to monitor the status of the issue and the next update will be provided here when Microsoft has fully resolved the issue.
Posted Sep 04, 2018 - 15:35 PDT
Update
Microsoft is continuing to work on mitigating the issue impacting Office Online and the Excel Online Previewer. We are continuing to monitor until the issue is resolved. We also recommend following https://status.office.com/ and https://azure.microsoft.com/en-us/status/ for the latest updates from Microsoft.
Posted Sep 04, 2018 - 12:11 PDT
Update
We are starting to see the recovery of Microsoft's services that impacted the ability to preview Excel spreadsheets and edit documents in Microsoft Online. We will continue to monitor to ensure full remediation.
We have identified an issue impacting our integration with Microsoft Online. Some users may receive an error while attempting to preview an Excel spreadsheet from the Box Web Application or edit documents in Office 365.