To start with, the oerr utility is not useful for the ORA-65096 ERROR mentioned below:-
ORA-65096: invalid common user or role name
Cause: An attempt was made to create a common user or role with a name that was not valid for common users or roles. In addition to the usual rules for user and role names, common user and role names must start with C## or c## and consist only of ASCII characters.
Action: Specify a valid common user or role name.
The solution to the ORA-06596 is to set a hidden parameter "_oracle_script". When you set the undocumented (hidden) parameter "_oracle_script"=true you can create the fred user without a C## in front of the user ID. However, this user will not used useful in a pluggable/container database:
connect system/manager as sysdba
alter session set "_ORACLE_SCRIPT"=true;
create user fred identified by flintstone;
grant dba to pubs;
Always consult Oracle support before using any hidden Oracle parameters. Oracle makes a distinction in multitenant databases for local vs. "common" user ID's wherein, the Common user IDs must always be created at the CDB level and start with a C### prefixes while, the Local users can only be created at the PDB layer, additionally also must use the CONTAINER clause set to CURRENT for the user to be created