LINE 1: IDENTIFY_SYSTEM error infinitum

Can anyone see why I keep getting the below "IDENTIFY_SYSTEM" error in
my logs when I start my replication database process?
I use "postgres primary" as my prefix in the syslog and "postgres
replication" as the replication one so their outputs are distinguishable.

Jun 30 14:10:25 postgres primary[19617]: [2-1] LOG: connection
received: host=192.168.2.8 port=55138
Jun 30 14:10:25 postgres primary[19617]: [3-1] LOG: connection
authorized: user=foobar database=postgres
Jun 30 14:10:25 postgres primary[19617]: [4-1] ERROR: syntax error at
or near "IDENTIFY_SYSTEM" at character 1
Jun 30 14:10:25 postgres primary[19617]: [4-2] STATEMENT: IDENTIFY_SYSTEM
Jun 30 14:10:25 postgres replication[19616]: [1-1] FATAL: could not
receive database system identifier and timeline ID from the primary
server: ERROR: syntax error at or near "IDENTIFY_SYSTEM"
Jun 30 14:10:25 postgres replication[19616]: [1-2] LINE 1:
IDENTIFY_SYSTEM
Jun 30 14:10:25 postgres replication[19616]: [1-3] ^
Jun 30 14:10:25 postgres replication[19616]: [1-4]
Jun 30 14:10:25 postgres primary[19617]: [5-1] LOG:

On primary's postgresql.conf I have this:
port = 5432
wal_level = archive # minimal, archive, or hot_standby
archive_mode = on max_wal_senders = 1 # max number of walsender
processes
#hot_standby = off

On the replication database's postgresql.conf I have this:
port = 5433
wal_level = minimal
archive_mode = off
#max_wal_senders = 0 # max number of walsender processes
hot_standby = off