DRIVERS-3416 : Summary of necessary driver changes Sync backpressure tests to test the requirement: A retry attempt will only be permitted if: [...] The command is a write and retryWrites is enabled or the command is a read and retryReads is enabled. To retry runCommand , both retryWrites and retryReads MUST be enabled. Passing these tests required non-trivial changes in the C driver and PyMongo. Commits for syncing spec/prose tests https://github.com/mongodb/specifications/commit/5711e4b748297600f27996412ffa179897836d4e adds the test cases. https://github.com/mongodb/specifications/commit/66317ed498196a62d3945f732781a545e8ceeb3d is a follow-up to avoid duplicate test names.