Class name is wrong or classpath is not set ERROR in Netbeans with Glassfish 5 server and JPAs - jpa

Question

I have a Web Application in Netbeans 11 (with JDK 8 installed), I have added the dependencies for mysql-connector-java-8.0.15.jar and I have generated the JPAs from my DB.
No error while building it.
But when I try to run it, the Glassfish server give me these errors (pastebin link).
This is my persistence.xml, that I set accordingly, is:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="InvoicesPU" transaction-type="JTA">
<jta-data-source>java:app/Invoices</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties/>
</persistence-unit>
</persistence>
And in my java class I call it by:
#Stateless
public class InvoiceEJB implements InvoiceEJBLocal {
#PersistenceContext(unitName = "InvoicesPU")
EntityManager em;
...
em.someMethod();
For completeness, I have no error during the compilation phase!
Anyone know how to solve it?

Answer 1

After some research I solved it in this way:
taking inspiration from a similar problem, I created the Connection Pool and the Resource in the Glassfish Admin Console as suggested by devmind following this.
I removed as dependency the mysql-connector-java-8.x.x.jar and I added the mysql-connector-java-5.x.x.jar
In the persistence.xml I set the JNDI name for the tag jta-data-source
And everything goes as expected!
I don't know how to make everything work with the latest version of the MySQL Connector but, at least, in this way my Web Application works.
EDIT: for latests versions of mysql-connector, as devmind has suggest you should set MysqlDataSource: from com.mysql.jdbc.jdbc2.optional.MysqlDataSource to com.mysql.cj.jdbc.MysqlDataSource as reported here.
I hope it's useful to someone else.

Answer 2

Try to put your JDBC driver jar to Glassfish domain's lib folder. I usually store them in lib/ext.

Answer 3

I do not remember if I got this info from some other post or from the Glassfish user manual but it solves the issue mentioned for me, i.e.: Class name is wrong or classpath is not set ERROR with Glassfish 5 or Payara server. I'm using Payara Server 5.2022.3 currently.
Add the latest connector j to your server/your_domain; in my case it is domain1 and this is the script after I cd to /bin:
C:\Program Files\payara-web-5.2022.3\payara5\bin>asadmin add-library --type app "C:\Program Files (x86)\MySQL\Connector J 8.0\mysql-connector-j-8.0.31.jar"
Where quoted string is the path where I keep my connector j.