Jirka I'm afraid that there could happen hundreds of things since steps are not probably detailed enough for reproducing your troubles. It would require how were your dataSources created - configuration, which DB you used etc.

Quite probably it will be some weblogic configuration error, but I don't know weblogic much, at least I found this, so you can try if it will help to you:
https://forums.oracle.com/forums/thread.jspa?threadID=949034

CCing also PetrH. Please don't you know if this error can happen due to our support? As I mentioned in my last comment I would expect badly configured dataSource in WL but Jirka told me that he was creating that DS thru the IDE.

BTW, Jirka ... please could you send more detailed steps to helps us detect where the issue could happen? Especially focus on step Nr.2. Thanks.

there is one more openjpa issue https://netbeans.org/bugzilla/show_bug.cgi?id=195674 on our side but is it necessary to use openjpa?

it may be also openjpa issue even I said above "on our side"

It seems similar like bug 195674. If I enable JPA 2.0 in WebLogic properties (EclipseLink is used in persistence unit then), it throws a different error. I expect that application created from templates should work with default values. Steps to create entity classes are as follows:

- open new file wizard
- choose "Persistence|Entity Classes from Database"
- select "sample" data source in combo box
- click "Add All"
- click Next
- provide arbitrary package name
- click Finish

later default may be changed and issues with nondefault openjpa may get less priority.
what's another issue with jpa2.0 on?

Moving to the proper category. BTW, couldn't it be duplicate of issue #194787?

I also found really similar openjpa issue, but the is not clear if it was just closed (and it was setup error) or if there were really changes to sources:
https://issues.apache.org/jira/browse/OPENJPA-1495
But I would believe the status there that the issue had to be really fixed and it's openjpa-1 bug.

yes in 194787 initial issue wasn't reproducible and it was used to resolve some others but initial was the same as in this issue.
It may have sense to look at what way datasource was created, how it was created? May be this datasource wasn't deployed to weblogic properly.

I created brand new domain using WebLogic configuration wizard. Then in the "Entity Classes from Database" wizard I created a new data source from sample derby connection. It was deployed to WebLogic server when I run project.

- run project (JPA 2.0 disabled) - stackTrace.txt
- enable JPA 2.0 in server properties
- restart server
- run project - stackTraceJPA2.0.txt
- create new project with entity classes and JSF pages from EC
- run project - it works

So, is it an issue of WebLogic, openjpa or IDE?

Created attachment 112439 [details]
Stack trace with JPA 2.0 disabled.

Created attachment 112440 [details]
Stack trace with JPA 2.0 enabled.

(In reply to comment #10)
> Created an attachment (id=112439) [details]
> Stack trace with JPA 2.0 disabled.

I'm afraid that this is not telling anything about this issue. Is it possible that you have timed out your session, refreshed old page, or not running properly server or app?

last one "Stack trace with JPA 2.0 disabled" is different from initial stacktrace, and looks like index page access issue and either index isn't valid or server is corrupted/broken etc.

with jpa2.0 on it's duplicate of issue "195674", org.apache.openjpa.persistence.PersistenceException: Neplatn� form�t �et�zce znak� pro typ int.
As I see. It seems jpa2.0 was enabled after application creation and it means openjpa is used instead of eclipselink or may be there is another issue.

I used Run project action and waited for new browser window to be opened.

(In reply to comment #14)
> I used Run project action and waited for new browser window to be opened.

I'm afraid that this mustn't be save enough, especially if you had enabled DoS. GF could also tried to refresh/restore your session and wasn't successful.

just tested initial steps
I have fresh 10.3.5 installation with some default domain created at installation, all default.
CReate web project on this server instance(with registration in the wizard) and with jsf framework addition.
Create new entity from DISCOUNT_CODE, with "myds" datasource creation in the wizard from connection to derby db.
create jsf from this entity with all default in the same package.
invoke Run

page is deployed successfully, neither initially reported not last one with index page access issue is reproducible.
attempt to access @Show All DiscountCode Items@ produce error from issue 195674 and nothing else.

Am I miss something?

Your steps are exactly the same as mine. First time I got a different exception and lastly the same as in bug 195674.

Ok, first time there may be some deployment issue with first time datasource configuration during deployment, it may be good to localize it if there any way to reproduce, I just have no this issue even with first time so it at least random as you have no this issue second time. And it may be not a persistence issue instead of bug 195674.

isn't reproducible/anyway low priority even if rarely reproducible as eclipsleink/toplink support is preferred and can be easily selected either on sever side or changed in persistence.xml