Engineer(s): Bernie Hackett Summary: In PYTHON-2152 , support for the "unspecified" UuidRepresentation was added to PyMongo and the bson.binary.Binary class was augmented to conform to the UUID specification. However, PyMongo's implicit encoding/decoding behavior still does not comply with this specification as these changes are backward-incompatible. We MUST make these changes as part of the PyMongo 4.0 release and include a section about the change in the migration guide. Cost in Eng Weeks: N/A - Bernie's spare time. Ongoing Update: Aiming to complete in FY22Q2, not setting specific end date Bernie is handling the small number of tickets in this epic in preparation for releasing V4 of the Python Driver. Not setting a specific timeline beyond FY22Q2 as Bernie is chipping away at this as he is able with a director's schedule. 2021-02-23: Aiming to complete in FY22Q1, not setting specific end date Bernie is handling the small number of tickets in this epic in preparation for releasing V4 of the Python Driver. Not setting a specific timeline beyond FY22Q1 as Bernie is chipping away at this as he is able with a director's schedule. Cost in Eng Weeks: N/A - Bernie's spare time. 2021-02-09: Aiming to complete in FY22Q1, not setting specific end date Bernie is handling the small number of tickets in this epic in preparation for releasing V4 of the Python Driver. Not setting a specific timeline beyond FY22Q1 as Bernie is chipping away at this as he is able with a director's schedule.