We’ve not touched this in some time, but I would expect the 1.x client to work generally.
The symptom doesn’t quite match this, but if you’re using a brand new 5.x cluster, you need to setup the users in a very specific way to be compatible with clients that are not RBAC ready.
Starting in 5.0, you need to create a user with the same name as the bucket for compatibility and give that user permissions to access the bucket. You can no longer create passwords directly on buckets in 5.0. Using a password is required.
For more info, see:
Couchbase SDKs (note cluster.authenticate() )