class ActiveRecord::ConnectionNotDefined

has not been defined.
Raised when a database connection pool is requested but

def initialize(message = nil, connection_name: nil, role: nil, shard: nil) 

def initialize(message = nil, connection_name: nil, role: nil, shard: nil)
  super(message)
  @connection_name = connection_name
  @role = role
  @shard = shard
end