Hi,
Thank you for posting your query on Symantec community.
This error can occur for the following reasons:
- Ports to the reporting server are blocked
- SEPM/PHP directory permissions
- IE security settings
- IIS permissions on virtual directories (e.g. IIS lockdown procedures, Active Directory permissions, etc...)
- Apache configuration issues
Refer this guide: The Home, Monitors, Reporting pages fail to appear when you launch the Symantec Endpoint Protection Manager or Symantec Protection Center.