This is a JNDI related exception. On the first page of your Weblogic JDBC/Data Source there is a text box for JNDI names. Fill this out very carefully paying special care to line breaks and blank spaces. The application parses this field and splits up entries that exist on separate lines as separate JNDI names. (You're allowed to have more than one) If, for example you have two extra line breaks after your JNDI names in the text field , Weblogic will complain that you already named a resource "" and can't have two resources registered as "".