Veeam ONE reports fail with caching service database connection errors

Report generation in Veeam ONE fails with 'Veeam ONE Caching Service Maintenance' error and HTTP 500 status from ReporterStateProvider, indicating Veeam ONE Caching Service cannot connect to PostgreSQL Reporting Database.

Check C:\ProgramData\Veeam\Veeam ONE\Logs\CachingService\Service.log and search upward for 'DB test failed:' to identify the specific connection error (password, SSPI auth, or service stopped). Apply the appropriate remediation based on the specific error found.