Checkpoint commit failure

Hi All,

We have the following xcdr message from the log:

xdc_vbucket_rep_ckpt:134] Checkpointing failed unexpectedly ( or could be network problem): {error, 500, <<"{“error”:“unexpected_reason”,“reason”:“killed”}\n">>}

from the ns_server debug log:

crash report:

initial call: xdc_vbucket_rep:init/1
pid: <0.25137.6965>

registered_name: []
exception exit: {failed_to_commit_checkpoint,
                    {error,500,                            <<"{\"error\":\"unexpected_reason\",\"reason\":\"killed\"}\n">>}}

What could be the reason? or what else is needed to troubleshoot this?
The source and destination server that replication goes to are in the same subnet, so there is not networking involved. The destination server item count is a bit less than the source item count.