javax.persistence.PersistenceException: Unable to build entity manager factory - exception

Question

When I'm trying to create a new EntityManager to persist my data, i get the following Error:
javax.persistence.PersistenceException: Unable to build entity manager factory
I using the JPA-Persistence Provider of Hibernate...
unluckily I couldn't find any helpful post in stackoverflow / with googling...
Does anybody have an idea where the cause of the error could lie?
Thank you for your help!
code-snippets:
creation of entitymanager
EntityManager em;
EntityManagerFactory fact = Persistence.createEntityManagerFactory("bachelordebug"); // Here it crashes
em = fact.createEntityManager();
stacktrace
javax.persistence.PersistenceException: Unable to build entity manager factory
at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:81)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:54)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
at com.uzh.platform.api.util.AssignmentUtil.findAll(AssignmentUtil.java:20)
at com.uzh.platform.api.services.GetAssignments.getAssignments(GetAssignments.java:22)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:151)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:171)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:152)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:104)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:402)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:349)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:106)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:259)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:318)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:236)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1010)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:373)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:382)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:345)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:220)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:156)
at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:233)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="bachelordebug" transaction-type="RESOURCE_LOCAL">
<!-- <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> -->
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<class>com.uzh.platform.data.dao.Assignment</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:postgresql://127.0.0.1:5432/bachelor"/>
<property name="javax.persistence.jdbc.user" value="bachelor"/>
<property name="javax.persistence.jdbc.password" value="bachelor14"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.connection.release_mode" value="after_statement"/>
<property name="connection.pool_size" value="1"/>
<property name="dialect" value="org.postgresql.Driver"/>
<property name="current_session_context_class" value="thread"/>
<property name="cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/>
<property name="show_sql" value="true"/>
</properties>
</persistence-unit>

Answer 1

(Question answered in comments and edits. See Question with no answers, but issue solved in the comments (or extended in chat) )
The OP wrote:
SOLVED
I finally found my error!
In my JPA-Entity class, I misspelled my Named-Query Annotation (even though I don't use it)
#NamedQuery(name="Assignment.findAll", query ="SELECT * FROM assignment")
of course one has to write that in capital Letters, i.e. "Assignment" (i.e. all terms like they appear in the service-class!)
3 days wasted with this stupid error - but now I learned how to do it! :-)
Thanks anyway for your help!

Answer 2

Since the error can indicate a lot of different causes it seems best to get to the cause examining the Hibernate DEBUG log statements (we use logback, but it should work in any other logging framework similarly):
With this you get a lot of output, but can determine the actually interesting classes (it is very likely you will spot the cause here already):
// (logback.groovy)
logger( "org.hibernate", DEBUG )
Which for us showed something like the following (where Mapping collection: foo.Bar.field -> some_tab_x was the info we needed to spot the faulty mapping):
07:32:43.720 D~ [main ~ main] [ : ] CollectionSecondPass:SecondPass: 67|
Second pass for collection: foo.Bar.field
07:32:43.720 D~ [main ~ main] [ : ] c.a.CollectionBinder:SecondPass: 823|
Binding a OneToMany: foo.Bar.field through a foreign key
07:32:43.720 D~ [main ~ main] [ : ] c.a.CollectionBinder:SecondPass: 861|
Mapping collection: foo.Bar.field -> some_tab_x
07:32:43.727 D~ [main ~ main] [ : ] ePersistenceProvider:gerFactory: 82|
Unable to build entity manager factory
07:32:43.743 E~ [main ~ main] [ : ] .l.f.m.m.MgFooTstJu:AndRethrow: 74|
MyException: unit test error loading Foo with id: 4342153208-2:
<java.lang.NullPointerException> =>
<javax.persistence.PersistenceException: Unable to build entity manager factory>
To restrict the logging again (if there are multiple places to fix your JPA mapping), we then used something like the following:
// (logback.groovy)
//logger( "org.hibernate", DEBUG ) // log everything
// infos on annotation mappping, e.g. getting NullPointerExceptions with
// javax.persistence.PersistenceException: Unable to build entity manager factory
logger( "org.hibernate.cfg.annotations.CollectionBinder", DEBUG )
(E.g. in Eclipse just use CTRL+SHIFT+T to search for the type you like to debug, if the log output does not show the complete classname)

Answer 3

I encountered the same error, and unfortunately the above answer didn't help me a lot. So I looked to other errors reported in my case where I found this error:
com.mysql.cj.core.exceptions.InvalidConnectionAttributeException: The server time zone value 'EEST' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
I solved it as specified the this answer and it's comments, by replacing my connection url with : "jdbc:mysql://localhost:3306/db?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC"
That solved all errors including the one noted in this question:
javax.persistence.PersistenceException: Unable to build entity manager factory
I hope this helps others coming across the same issue I faced.

Answer 4

add the id annotation in your entity class
#Entity
public class yourClass{
#Id
private Long id;
...
}