The "Upgrading to PostgreSQL 12 RC 1" references v11 rather than v12:
"To upgrade to PostgreSQL 11 RC 1 from Beta 4 or an earlier version of PostgreSQL 11, ..." Regards, -- Sehrope Sarkuni Founder & CEO | JackDB, Inc. | https://www.jackdb.com/
The "Upgrading to PostgreSQL 12 RC 1" references v11 rather than v12:
"To upgrade to PostgreSQL 11 RC 1 from Beta 4 or an earlier version of PostgreSQL 11, ..." Regards, -- Sehrope Sarkuni Founder & CEO | JackDB, Inc. | https://www.jackdb.com/