Logstash Loki payload failed error

Hi All,
I am using logstash-loki-output plugin to ingest data to Loki. But I keep getting
loki - failed payload {:payload=>...
Below is my logstash.conf file. I have kept it quite simple

    input {  
      s3 {
       bucket => "lxx"      
       region => "us-west-2"     
       interval => 60
       prefix => "test/"
       watch_for_new_files => true
       additional_settings => {
          force_path_style => true
          follow_redirects => false
        }   
      }
    } 
    filter {
    }
    output {
      loki {
        url => "http://loki-write:3100/loki/api/v1/push"
	}
     stdout{
       codec => json
     }
    }

I can see output with stdout …but with loki output I keep on getting error

Any hints will really help.
TIA