Rebalance exited with reason service_rebalance_failed index linked_process_died no_connection index-service_api

[Que Onda?]

Hi, can someone help with this error while trying to rebalance?

This is a four server cluster (Version running: Enterprise Edition 5.1.1 build 572) which started giving the following error during rebalance:

Rebalance exited with reason {service_rebalance_failed,index, {linked_process_died,<12792.14263.612>, {no_connection,"index-service_api"}}}

Any ideas what I could check/do about it?

Thanks,

Leo