In Netbeans 7.4
I used to create a Persistence Unit
by choosing a JNDI name and then a database connection. In Netbeans 8
I repeated the same process and started to give the old error
Invalid resource : jdbc/something__pm
I also created a JDB resource with a new connection pool and the problem still remain. My way to solve this mistery was to delete line jdbc/something from persistence source. Is there any problem with this solution?