pyodbc upsert error - SQL contains 0 parameter markers, but 3 parameters were supplied', 'HY000'

Question

I am using pyodbc, impala driver for kudu on cloudera 5.16, Python 3.6.10 to do an upsert into kudu table. Insert works fine but upsert fails. I am getting an error: SQL contains 0 parameter markers, but 3 parameters were supplied', 'HY000' . The code looks like below:

import pyodbc
conn = pyodbc.connect('DSN=my-impala-dsn',autocommit=True) 
crsr = conn.cursor() 

crsr.execute("UPSERT INTO mydb.mytable (col1,col2,col3) values(?,?,?)", val1,val2,val3)

Any thoughts on the error?