splunk upgrade from 7.3.3 to 8.0.0 failed (Could not create path D:\splunk\data\index\_metrics\db appearing in indexes.conf: 5 )

Hi, anyone know how to solve this problem? Could not create path D:\splunk\data\index\_metrics\db appearing in indexes.conf: 5 Validating databases (splunk valiadated) failed with code '1' as we have tried to use Admin account already and can access to this folder D:\splunk\data\index\_metrics. but we cannot upgrade successfully.