ORA-28009

Hi everyone

I have started CodeIgniter recently and I have a problem connecting to my DB (Oracle)

Indeed I have an error message telling me that I have to connect as SYSDBA or SYSOPER.

I have read a topic from this forum but he is from 2012 and the links doesn't help.

This is the error message : 

Message: oci_connect(): ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
Filename: oci8/oci8_driver.php
Line Number: 239

If someone could help me that would be great, this is for my diploma work.

Thank you 

PS : I already had this problem in "simple" php, I fixed it by puting the session_mode argument in the "oci_connect" function.