Unique Field - no unique constraint matching given keys - postgresql

Question

I have three tables in a postgresql database, namely tec_configurations, tep_cores and tep2tec_bindings. The table tec2tep_bindings references to the primary key fields of the first two tables. The related create statements per table are listed in below sql snippets 2,3 and 4. I get the error indicated in the 1st snippet below. Could you please tell me how I can fix this error? The 'id' field in table TEC_CONFIGURATIONS is already unique since it is a primary key. So, I don't see a reason to get this error message.
SNIPPET 1 (Error message):
ERROR: there is no unique constraint matching given keys for referenced table
"tec_configurations"
SNIPPET 2 (TABLE tec_configurations):
CREATE TABLE IF NOT EXISTS TEC_CONFIGURATIONS (
ID SERIAL PRIMARY KEY,
TEC_ID INT NOT NULL,
HANDLER_MAC TEXT NOT NULL,
PRIMARY_MAC TEXT,
SECONDARY_MAC TEXT,
TERTIARY_MAC TEXT,
EXPECTED_FLOWS INT DEFAULT 0,
VERSION INT DEFAULT 0,
UUID TEXT DEFAULT NULL );
SNIPPET 3 (TABLE tep_cores):
CREATE TABLE IF NOT EXISTS TEP_CORES (
ID SERIAL PRIMARY KEY,
MAC TEXT,
UUID TEXT,
CORE_NO INT DEFAULT 0);
SNIPPET 4 (TABLE tec2tep_bindings)
CREATE TABLE IF NOT EXISTS TEC2TEP_BINDINGS (
ID SERIAL PRIMARY KEY,
TEC_ID_FK INT NOT NULL REFERENCES TEC_CONFIGURATIONS(ID),
TEP_CORE_ID_FK INT NOT NULL REFERENCES TEP_CORES(ID),
REPLICA_RANK INT DEFAULT 0);

Answer 1

Wild guess, since you're issuing create table if not exists rather than create table: one of the tables exists without the needed unique key (e.g. from lack of a primary key).
(If correct, I'd add this note. Some Postgres core devs were hostile to the idea of adding if exists and if not exists constructs, objecting thus: "What is supposed to happen when you create table if not exists, silently "succeed", and the existing table has a schema different from the one you were hoping for?")