EndPoint may be null during SendAsync

[04/01/2020 12:05:47] warn: xxx.Service.DataService[0]

      Error getting document key XXXXXXXXXXXXX from default collection: Value cannot be null. (Parameter 'endPoint')

====>ErrorMsg: System.AggregateException: One or more errors occurred. (Value cannot be null. (Parameter 'endPoint'))

       ---> System.ArgumentNullException: Value cannot be null. (Parameter 'endPoint')

         at Couchbase.CouchbaseBucket.SendAsync(IOperation op, CancellationToken token, Nullable`1 timeout)

         at Couchbase.Core.Retry.RetryOrchestrator.RetryAsync(BucketBase bucket, IOperation operation, CancellationToken token, Nullable`1 timeout)

         at Couchbase.KeyValue.CouchbaseCollection.ExecuteLookupIn(String id, IEnumerable`1 specs, LookupInOptions options)

         at Couchbase.KeyValue.CouchbaseCollection.GetAsync(String id, GetOptions options)