PostgreSQL upgrade best practices, please share your thoughts

Hi all,

currently I am preparing my session (PostgreSQL upgrade best practices) for the Swiss PGDay 2017 (http://www.pgday.ch/2017/). What I plan to come up with is:

- Support policy
- Release notes
- Why it is important to upgrade (or at least to patch to the latest minor release)
- Minor version upgrades vs major version upgrades
- The importance of version specific directories
- What to take care of with tablespaces
- What to take care of with extensions
- Pain points with (missing) statistics after the upgrade
- Upgrades using pg_dump
- Upgrades using pg_dumpall for global objects and then pg_dump in parallel
- pg_upgrade (check mode, normal mode vs. link mode, upgrading with streaming replication configurations)
- Getting support (mailing lists)
- PostgreSQL 10: Logical replication

What I would like to ask you:
What would you add to the above list?
Can you please share what issues you had when upgrading and maybe how you solved it? I'd love to include as much information as possible.

Thanks in advance
Daniel