That was never true for major version upgrades: e.g. 9.4.x -> 9.5.x 9.5.x -> 9.6.x 9.6.x -> 10.x (they changed versioning since 10.x) 10.x -> 11.x 11.x ->

That was never true for major version upgrades: e.g. 9.4.x -> 9.5.x 9.5.x -> 9.6.x 9.6.x -> 10.x (they changed versioning since 10.x) 10.x -> 11.x 11.x -> 12.x and so on You couldn't just drop new version and assume it will work, the database needed to be converted to new format, pg_upgrade tool was created for this operation. By default it generates a new database in new folder. There's also a flag that uses hard link for files that didn't change between versions (it usually only takes a minute or less), but with the caveat that if upgrade is not successful and you run the new version of the database, you'll have to use backup to restore old version (since the new version might modify the files). There's also pg_dump/pg_restore, but this is the slowest way.