@mudgilgaurav please read this and specifically the "Also be patient" part.
Do you have a more detailed stack-trace in your logs?
Judging from the error it seems that http://bucketname.s3.ap-south-1.amazonaws.com/ does not exist. Did you create it?
Also, in this old version, if you define the region you don't need to define the endpoint.
In 6.0 you need to define the endpoint only as region has been removed.
Any chance you can also upgrade? At least to latest 2.4?