Upgrade to 5 file descriptors Issue

I am trying to upgrade ES cluster to 5 and using _plugin/elasticsearch-migration/ when i am running cluster checkup and its complaining about issue At least 65536 file descriptors must be available to Elasticsearch first before i can upgrade, Here is what my node stats looks

when i call _nodes/stats/process?filter_path=.max_file_descriptor i see below value

{"process":{"max_file_descriptors":-1}}}}

when i call _nodes/_local?process=true&pretty=true i see below value but not with process block

"max_file_descriptors" : "65536"

below entries in /usr/share/elasticsearch/elasticsearch.sh

MAX_OPEN_FILES=65536
MAX_LOCKED_MEMORY=unlimited

any idea what the issue is

Maybe just one node is reporting -1 as max file descriptors? Can you introspect the response of the node info api for all nodes? (Either by sending nodes/local?process=true to all nodes or nodes/stats/process to s single node (this should include the max file descriptions for all nodes in your cluster) ).

single node or cluster still it shows max_file_descriptor=-1,by the way it displays open files 65536 when i call ulimit -n, what options i have now to upgrade to 5 ?

Not sure why this happens. But you can easily verify if this is problematic for ES 5. ES 5 checks for this at startup and fails if it doesn't have enough file descriptors. So if you just start a temporary ES 5 node on your machine (don't bind to localhost, that will enable dev mode) and if it starts without a problem then I think the warning that migration plugin is showing you, can be ignored.