• PostgreSQL is deployed externally using the Crunchy Postgres Operator(v5.0.4 and v5.0.3), which  has deployed PostgreSQL instance 10.18.
• When deploying 3scale using external databases, system-app-X-hook-pre pod throws the following error

rake aborted!PG::ConnectionBad: SCRAM authentication requires libpq version 10 or above/opt/system/vendor/bundle/ruby/2.6.0/gems/pg-0.21.0/lib/pg.rb:56:in `initialize'/opt/system/vendor/bundle/ruby/2.6.0/gems/pg-0.21.0/lib/pg.rb:56:in `new'
/opt/system/vendor/bundle/ruby/2.6.0/gems/pg-0.21.0/lib/pg.rb:56:in `connect' 

• The error seems to be indicating, that the used ruby Postgres libs are to old and do not support scram authentication(https://rubygems.org/gems/pg/versions/ => 0.21.0 - June 12, 2017 (209 KB) )
• Requesting to upgrade the PostgreSQL Ruby libs to a later version which supports  scram-sha-256

More information
https://access.redhat.com/articles/2798521 (supported version of postgres is 10.18)
https://www.cybertec-postgresql.com/en/from-md5-to-scram-sha-256-in-postgresql/