No handler found for uri [/fi7/29/20191b1amt-6.8.1-YYYY.MM.DD/_mapping] and method [GET]"

hi ,
i am using grafana version (6.2.5) but i am facing problem while adding datasource it is showing no handler found for uri [/fi7/29/20191b1amt-6.8.1-YYYY.MM.DD/_mapping] and method [GET]"