Need help with Optimism

l2geth cannot connect to data service. Can anyone help?

INFO [05-28|17:03:41.407] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused" INFO [05-28|17:03:51.406] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused" INFO [05-28|17:04:01.406] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused" INFO [05-28|17:04:11.406] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused" INFO [05-28|17:04:21.407] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused" INFO [05-28|17:04:31.407] Cannot connect to upstream service msg="Cannot connect to data service: Cannot fetch eth context: Get "http://localhost:7878/eth/context/latest": dial tcp [::1]:7878: connect: connection refused"