Apologies if the formatting for this is messed up, I have just joined the list but would like to reply to a thread that started before I joined, so I have to copy and paste relevant items in. Specifically, I have comments on this: - What are other people's experiences with upgrading pandas? And would more bug-fix releases actually ease the upgrading? I work for a large company with an established Python code base (3+ years of maintenance, tens of users). Pandas and numpy are heavily used throughout the code base. In our experience, upgrading pandas is usually quite an involved exercise. When we upgraded from 0.15.2 to 0.17, it took several passes, as follows: * attempted to upgrade from 0.15.2 to 0.16.1: Found the following bugs, raised the following PRs https://github.com/pydata/pandas/issues/10181 / https://github.com/pydata/pandas/pull/10188 https://github.com/pydata/pandas/issues/10195 / https://github.com/pydata/pandas/pull/10196 https://github.com/pydata/pandas/issues/10193 / https://github.com/pydata/pandas/pull/10379 * The above fixes went into 0.16.2 and 0.17.0 so we decided to wait for 0.17.0. * Tried 0.17.0: Found https://github.com/pydata/pandas/issues/11372 and https://github.com/pydata/pandas/issues/11370 * https://github.com/pydata/pandas/issues/11372 was fixed in 0.17.1 but not https://github.com/pydata/pandas/issues/11370 (targeted 0.18.0) * In the end we went with an intermediate build: 0.17.1.post78+g158e85a in the normal git versioning parlance. ( https://github.com/pydata/pandas/pull/11427 was the specific item that we needed- to fix issue 11372 above). We chose not to wait for 0.18.0 because that contains possibly breaking changes to resample. We judged that it was better to go with a known non-official intermediate build of master, that passed all our tests, than to risk another cycle of chasing bugs. We found that from 0.15.2 to 0.17.1, each release fixed one or more issues that affected us but also introduced other issues. I describe this just to add a data point and relate our experience with upgrading, rather than to shout for massive changes in the release process.The main things that hit us were edge cases breaking when core classes were refactored. Thanks, PC