Viewing SharePoint PDF files via Prisma browser is failing

Dear @Callie Hagedorn,

Thank you for reaching out to Microsoft Q&A forum.

I understand you're having trouble viewing SharePoint PDF files via the Prisma browser. From my research, it’s likely that Prisma is being identified by SharePoint as an "unmanaged" or "untrusted" client during the specific handshake required for inline PDF rendering. This is the reason why standard browsing works, but the specialized PDF preview engine which follows a different authentication path is failing to receive the necessary security tokens. The error message X-Msdavext_error "Access denied" is a common indicator that the browser is attempting to use a legacy WebDAV or "File Open" protocol. This protocol requires an active, persistent session, which Prisma’s security architecture may intentionally isolate to maintain secure browsing practices.

As a forum moderator, I genuinely wish I could directly access your account or delve into the backend systems to diagnose and fix this for you. However, our role here is limited to providing general guidance and solutions that can be applied by users.  

For problems of this nature, I recommend that the Global Admin in your organization create a service request with Microsoft Support. A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis. Ask The Global Admin in your organization to create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin. If you don't know who your IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support 

For additional assistance, use this link to find the appropriate contact number from your region: Global Customer Service phone numbers - Microsoft Support 

I truly hope you get your issue resolved swiftly. Please know that even though I can't directly intervene, directing you to the correct, specialized support is the most effective help I can provide from my position. Thank you for your patience and understanding. Let me know if you need anything else. have a wonderful day.

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