This message keeps coming up: Do you want to download"AppcacheManifestHandler.ashx"?

Same issue in July

Anything “end user” can do that is quick?

I have the same issue as Mr Tunberg. It's intensely annoying. What happens if I click the download button?

Hi Mr. Tunberg,

Thanks for reaching out to Microsoft Community Support.

That message about downloading "Do you want to download 'AppcacheManifestHandler.ashx'?" — is likely caused by a misconfiguration on the Outlook web server or a caching issue in the mobile browser or app. This file is part of Outlook Web Access (OWA) and is used for offline caching, but it shouldn't prompt for download.

To resolve this, Microsoft’s support team will need to step in. 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.    

As forum moderators, we don’t have access to the detailed logs or backend systems needed to troubleshoot this effectively due to privacy and security constraints. For that reason, the most efficient solution would be to contact Microsoft’s support team directly.  

For the standard procedure outlined above, Office 365 global administrators may need to contact the Office 365 support team by submitting a service request.    

Here’s what your Office 365 Global Admin should do next:       

1. Submit a Service Request: The Global Admin should 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 | Microsoft Learn.
2. Find Your Microsoft 365 Admin: If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support
3. Call Microsoft Support: For additional assistance, use this link to find the appropriate contact number: Customer service phone numbers - Microsoft Support
4. Contact a Reseller (if applicable): If your Office 365 subscriptions are managed through a federated partner or reseller and the Global Admin cannot open a service request, they should contact the reseller’s support provider. The reseller can assist with initiating the request and coordinating with the Office 365 support team.

Note: If you’re an end-user, please coordinate with your Office 365 Global Administrator to handle these steps.    

Best Regards,

Camila Th- MSFT | Microsoft Community Moderator