DRIVERS-2948 : Summary of necessary driver changes If the driver exposes the authentication mechanism in a public API, then: Deprecate MONGODB-CR and raise an error indicating to the user that MONGODB-CR is no longer supported in MongoDB 4.0 and subsequently the current driver version. If the driver does not expose the authentication mechanism in a public API then: Completely remove MONGODB-CR functionality from the driver. If not already done with DRIVERS-2938 sync the auth legacy spec tests to https://github.com/mongodb/specifications/pull/1611 Commits for syncing spec/prose tests (and/or refer to an existing language POC if needed)   https://github.com/mongodb/mongo-python-driver/commit/ad3292e39b0490db354735a803911bfd6943ee65 Context for other referenced/linked tickets  This should be done after DRIVERS-2511 (remove support for MongoDB 3.6)