OCI-46079
unable to complete the operation with the specified external principal name "string"
Cause
The specified external principal name was either the same as an existing Oracle Real Application Security (RAS) principal, or the principal name was still cached in the database shared pool.
Action
To use this external principal name, drop the RAS principal with the same name and try again. If the same error occurs again, you must flush the database shared pool using the ALTER SYSTEM FLUSH SHARED_POOL statement. Another option is to specify another external principal and retry the operation.