. /opt/oracle/db/tech_st/19.3.0/prodcdb_erpdb.env
cd /opt/oracle/db/tech_st/19.3.0/dbs
cp orapwprodcdb orapwprodcdb.orig
mv orapwPROD orapwPROD.orig (File doesnot exists)
orapwd file=/opt/oracle/db/tech_st/19.3.0/dbs/orapwPROD password=manager123* entries=10 ignorecase=y
orapwd file=/opt/MG/oracle/PROD/db/tech_st/12.1.0/dbs/orapwPROD password=mikmanager entries=10 ignorecase=y
orapwd file=/opt/MG/oracle/PROD/db/tech_st/12.1.0/dbs/orapwTEST password=mikmanager entries=10 ignorecase=y
Now execute:
Connect Sqlplus / as sysdba
alter user sys identified by <password>
Bounce DB
If SYS user can connect with wrong password as well.
Edit sqlnet.ora file and add:
SQLNET.AUTHENTICATION_SERVICES=(NONE)