Java SDK (Couchbase Server 6.5) failed with AuthenticationFailureException:

Hi, I have problem connecting to my local Couchbase cluster (created accroding to this guide):

[cb-events] ERROR - [][SaslAuthenticationFailedEvent][188ms] Authentication Failure {"coreId":"0xd220a2fd00000001","local":"/","remote":""}
[cb-events] WARN com.couchbase.endpoint - [com.couchbase.endpoint][EndpointConnectionFailedEvent][563ms] Connect attempt 1 failed because of AuthenticationFailureException: Authentication Failure {"circuitBreaker":"DISABLED","coreId":"0xd220a2fd00000001","remote":"","type":"KV"}
com.couchbase.client.core.error.AuthenticationFailureException: Authentication Failure {"status":"UNKNOWN"}
        at java.base/

Basically, I copy & paste code from official Java SDK doc:

public class Couchbase {
  private static Logger log = LoggerFactory.getLogger(Couchbase.class);

  private Cluster cluster;
  private Bucket bucket;
  private Collection coll;

  public Couchbase(String url, String uname, String pwd, String bucket) {
    this.cluster = Cluster.connect(url, uname, pwd);
    this.bucket  = this.cluster.bucket(bucket);
    this.coll    = this.bucket.defaultCollection();

then in main class:

Couchbase cb = new Couchbase("", "user", "123456", "testbucket");

The user i used was created with full admin right.

Initially I was searching for Erlang/Elixir driver but found none! So, I turned to Java as last resort to write a HTTP-based driver for my Elixir app. I really like the KV style and redundancy model of Couchbase. Hope this works out…

Thanks a lot!