Amazon S3 Source Connector returns "Unable to read S3 objects with the provided bucket and path."

Amazon S3 Source Connector returns "Unable to read S3 objects with the provided bucket and path., but I think there is no problem in my config.
Are there any problem in my config? It’s clear that I made the same bucket and folder in s3.

curl -X PUT -H  "Content-Type:application/json" \
http://localhost:8083/connectors/s3-connector/config -d '
{
  "connector.class": "io.confluent.connect.s3.source.S3SourceConnector",
  "tasks.max": 1,
  "mode": "GENERIC",
  "topic.regex.list": "topics:.*",
  "s3.bucket.name": "s3-connector",
  "topics.dir": "topics",
  "format.class": "io.confluent.connect.s3.format.avro.AvroFormat"
}
'


This was because I did add a specific s3.region in config. The default value was us-west-2, but I didn’t use it.

Amazon S3 Source Connector Configuration Properties | Confluent Documentation