Error 'ORA-01741: illegal zero-length identifier' appears when creating or updating a row with the Schema Browser
Using insert / update statements to create records works fine. The problem only appears when trying to do this with the Schema Browser.
This problem appears because the Oracle username contains a dot ( For example : 'TE.ST') and Toad doesn't handle these usernames.
Use the insert / update statements in the SQL Editor instead of using the Schema Browser
Waiting for fix in a future release of Toad For Oracle