Error: ORA-00911 invalid character

When trying to run this query on cx_Oracle in python

Insert into orange.cp4_freeze_tasks (
SELECT distinct cust_id, 'C' 
  FROM (SELECT f.cust_id, cust_site, debt_invoiced + debt_no_invoiced deuda,
     DECODE (d.manual_level, 0, cp_level, manual_level) nivel,
     (SELECT nvl(freeze_limit,9999999999)
        FROM orange.cp4_level_config
       WHERE site_id = cust_site
         AND cplevel =
                  DECODE (d.manual_level,0, cp_level,manual_level)) freeze_limit
   FROM orange.cp4_freezed_customers f, orange.cp4_debt_status d
  WHERE f.cust_id = d.cust_id) c
 WHERE deuda <= freeze_limit / 2 and not exists (Select 1 from orange.cp4_freeze_tasks 
where cust_id = c.cust_id and task_status = 'C'));commit;

I'm receiving the following error:

cx_Oracle.DatabaseError: ORA-00911: invalid character

Already tried the solution from other questions: Deleting the last semicolon.

Any idea how to solve it?

Going to guess it's this that's causing the problem:

where cust_id = c.cust_id and task_status = 'C'));commit;

You've got two SQL statements in the one query. Remove the ;commit;. Your insert statement should now work. Change your python and add this after you run the insert:

connection.commit()

Obviously change connection to fit the actual variable name you use.