Documentation for converting legacy compilers only specifies opening port 5432 from the compiler to the master. If the client uses an external PostgreSQL node, these instructions will not work.
(this is also incorrect on 2019.7 docs)
Open port 5432 from compilers to your master.
Open port 5432 from compilers to the node hosting Puppet’s PostgreSQL, typically the master.
The port required for converting legacy compilers needs to account for more than just standard installations.