Proper syntax for upsert insert update psycopg2 - postgresql

Question

I have a table that I created in postgresql:
> CREATE TABLE issuer(
> cik char(10) NOT null ,issuer_name char(150) NOT NULL ,trading_symbol char(10) NOT
> NULL ,SIC char(6) NOt NULL
> ,date_added timestamp NULL DEFAULT
> CURRENT_TIMESTAMP ,CONSTRAINT issuer_pk PRIMARY key (cik) );
I am trying to either update a row if it exists or insert it if it doesn't.
I have searched the documentation on how to make this work, but I am baffled by the errors I get.
I have a function that I call
io = postgres_update_issuer(con,cur,cik,coname,ticker,'')
When I call this function, python calls threading and then quits.
Here is the function I call:
def postgres_update_issuer(conn,cur,issuer_cik,name,ticker,sic):
sql = """
INSERT INTO issuer ( cik,issuer_name,trading_symbol,SIC)
VALUES (%s,%s,%s,%s)
ON CONFLICT (cik)
DO UPDATE SET
(issuer_name,trading_symbol,SIC )
= (EXCLUDED.issuer_name, EXCLUDED.trading_symbol, EXCLUDED.SIC)
;"""
try:
# data = (issuer_cik,name,ticker,sic)
cur.execute(sql,(issuer_cik,name,ticker,sic) )
return True
except (Exception, psycopg2.DatabaseError) as error:
print(error)
When I change the function to this, I get the couldn't move all fields error message:
def postgres_update_issuer(conn,cur,issuer_cik,name,ticker,sic):
sql = """
INSERT INTO issuer ( cik,issuer_name,trading_symbol,SIC)
VALUES (%s)
ON CONFLICT (cik)
DO UPDATE SET
(issuer_name,trading_symbol,SIC )
= (EXCLUDED.issuer_name, EXCLUDED.trading_symbol, EXCLUDED.SIC)
;"""
try:
data = (issuer_cik,name,ticker,sic)
cur.execute(sql,(data )
return True
except (Exception, psycopg2.DatabaseError) as error:
print(error)
What is the correct way to do this. I am using python 3.6 psycopg2, and postgresql 10