ES 6.4.2 - error when trying to snapshot cluster to S3 bucket

[NadavKal (Nadav Kallenberg)]

i have open a new bucket on S3 and added full S3 permissions to the cluster instance Role.
but when attempting to snapshot like this:

/_snapshot/s3_repository
{
"type": "s3",
"settings": {
"bucket": "my-bucket",
"region": "us-east-1"
}
}

i'm getting:
{
"error": {
"root_cause": [
{
"type": "remote_transport_exception",
"reason": "[ip-10-1-0-50][10.1.0.50:9300][indices:admin/create]"
}
],
"type": "string_index_out_of_bounds_exception",
"reason": "String index out of range: 0"
},
"status": 500
}

10.1.0.50 has repository-s3 plugin installed and the elasticsearch service has been restarted.

could any one tell me what's causing the error and how to fix it?

[DavidTurner]

This shouldn't be happening. Can you provide the stack trace that goes with this exception? It should be in the Elasticsearch log file.

[NadavKal (Nadav Kallenberg)]

thanks @DavidTurner, but i've already solved it.
i don't know why but it didn't work from the kibana dev tool.
it did work though with a curl and from cerebro.