' This error was produced on Ruby Driver version 2.6.x and earlier. This error is raised when the driver is unable to connect to the server. In order to solve this, you can try the following: - Update the driver to the most recent 2.x release. - Ensure that the port number is correct in the URI/connection string, or the host list. - If you are connecting to Atlas, ensure that the firewall rules are configured correctly. See the documentation on `Cluster Security `_. - If your application uses a forking web server, see the documentation on :ref:`Forking `. See more on this issue here: `RUBY-1281 `_. ``OperationFailure`` When Reading ``local`` Database With Auth On ================================================================= If you are getting the following error when trying to read the ``local`` database: .. code-block:: ruby Mongo::Error::OperationFailure: not authorized on local to execute command { find: "oplog.rs", filter: { ts: { $gte: Timestamp 1497449043000|0 } }, sort: { $natural: 1 } } (13) You can fix this by adjusting the roles your user has and ensuring that it has privileges to the local database. If you specifically want to access the oplog, you can also create a custom role with read access to the local database's ``oplog.rs`` collection. You can find more information about role management `here `_. You can find more information about this issue here: `MONGOID-4446 `_. ``SocketTimeoutError`` and name resolution errors on EC2 ======================================================== Some users reported getting the following error: .. code-block:: ruby Exception Mongo::Error::SocketTimeoutError Error execution expired /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/socket/ssl.rb:57:in `pack_sockaddr_in' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/socket/ssl.rb:57:in `block (2 levels) in connect!' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/socket.rb:199:in `handle_errors' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/socket/ssl.rb:57:in `block in connect!' /usr/lib/ruby/2.3.0/timeout.rb:101:in `timeout' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/socket/ssl.rb:56:in `connect!' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/address.rb:172:in `connect_socket!' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/server/connection.rb:86:in `connect!' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/server/connectable.rb:84:in `ensure_connected' /var/lib/gems/2.3.0/gems/mongo-2.5.0/lib/mongo/server/connection.rb:256:in `write' This error was last reported on Ruby Driver version 2.5.1, so updating the driver can potentially solve this issue. A user has reported that they solved this issue as follows: DNS servers on EC2 are generated in /etc/resolv.conf by default. Following the answer `here `_ and setting the nameservers to Google NS I was able to fix this issue. You can find more information about this issue here: `MONGOID-4527 `_. ``Mongo::Auth::Unauthorized`` User is Not Authorized to Access ============================================================== Some users reported getting the following error: .. code-block:: ruby Mongo::Auth::Unauthorized: User ... is not authorized to access ... After upgrading to Ruby Driver version 2.5+, the driver was changed to use the scram authorization mechanism by default. This error might be happen if the authorization mechanism your user was created with does not match the authorization mechanism used by the driver. You can specify the preferred authorization mechanism using the ``auth_mech`` option in your ``mongoid.yml`` file. See more on this issue here: `RUBY-1281 `_.