Microsoft Graph API Powerpoint Viewer - Previewer is failing to load

Question

Description: Users are unable to view PowerPoint slides on our platform. When navigating to a resource containing PowerPoint slides, the viewer attempts to load but ultimately fails, falling back to a prompt asking the user to download the file instead.

Steps to reproduce:

1. Navigate to a resource containing PowerPoint slides
2. Observe the viewer attempt to load, then fail and prompt for download

Additional notes: Extracting the iframe's URL (Sharepoint URL) and navigating to it directly also results in a failure, suggesting the issue may originate upstream with SharePoint rather than with our viewer implementation.

1. We are using the Microsoft Graph driveItem: preview - https://learn.microsoft.com/en-us/graph/api/driveitem-preview?view=graph-rest-1.0 .
2. The issue seems to happen for all PPT files.
3. Tested using Chrome, Firefox, Safari and the issue is reproducible on all 3

Screenshot 1:

Grabbing the Iframe URL (Sharepoint URL) and navigating to that URL generates the following error page.

**
Screenshot 2:**

When navigating to a Powerpoint resource directly in our digital platform, the viewer hangs on the screen below as it attempts to load the slides. Eventually it fails, and you will see what is in screenshot 2.

Screenshot 3:

After the viewer fails to load, eventually the screen below appears which allows the user to download the file.

Answer 1

Dear Manpreet Komal,

Thank you for the detailed information and screenshots. Based on what you've shared, the issue does not appear to be related to a specific browser, as you've reproduced it in Chrome, Firefox, and Safari. Additionally, the preview URL generated by the Microsoft Graph driveItem: preview API also fails when opened directly.

As a few troubleshooting steps, could you please check the following?

• Does the issue occur with a brand-new PowerPoint file containing only a single slide, or only with existing presentations?
• Are you able to open the same PowerPoint files successfully in PowerPoint for the web directly from SharePoint?
• Does the behavior occur for files stored in all SharePoint sites/libraries, or only in a specific location?
• Verify that affected users have at least Read permissions to the file and document library.
• Test from a different network (such as a mobile hotspot) to rule out network filtering.
• You can try the Graph driveItem: preview request using Graph Explorer and confirm whether a valid preview URL is returned.

If possible, the IT Admin can check whether any Conditional Access policies, network restrictions, or security products might be blocking access to Microsoft 365 endpoints used by the preview service.

Note: How do I find my Microsoft 365 admin?

• A Conditional Access policy that restricts access to SharePoint Online, Office for the web, or unmanaged devices. For reference: Build a Conditional Access policy
• A corporate proxy or firewall blocking connections to domains such as *.officeapps.live.com, *.office.com, *.sharepoint.com, or *.microsoft.com.​‌
• VPN or network policies that affect access to Microsoft 365 endpoints.

Since this is a community forum, I do not have access to the service-side logs. If the troubleshooting above does not identify the cause and the issue still persists with all browsers, I recommend opening a support ticket with Microsoft 365 Support in the M365 Admin Center and providing the preview URL, sample files, timestamps, and the browser logs/screenshots. This will allow the support team to review the SharePoint and Office Online preview service logs in greater detail. For reference: Get support for Microsoft 365 for business