ERREUR lors d'exécution d'une application sur jdeveloper12c

bonjour à tous,

j'ai telechargé jdeveloper 12c pour programmer des applications ADF web. Au début tout va bien (en testant qq examples) mais depuis une semaine, une erreur se produit et je n'arrive pas trouver une solution (je suis débutante et je programme souvent avec netbeans)
voiçi l'erreur:

<5 avr. 2016 12 h 38 CEST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to STARTING.>
<5 avr. 2016 12 h 38 CEST> <Info> <WorkManager> <BEA-002900> <Initializing self-tuning thread pool.>
<5 avr. 2016 12 h 38 CEST> <Notice> <LoggingService> <BEA-320400> <The log file C:\Users\dell\AppData\Roaming\JDeveloper\system12.1.2.0.40.66.68\DefaultDomain\servers\DefaultServer\logs\DefaultServer.log will be rotated. Reopen the log file if tailing has stopped. This can happen on some platforms, such as Windows.>
<5 avr. 2016 12 h 38 CEST> <Notice> <LoggingService> <BEA-320401> <The log file has been rotated to C:\Users\dell\AppData\Roaming\JDeveloper\system12.1.2.0.40.66.68\DefaultDomain\servers\DefaultServer\logs\DefaultServer.log00016. Log messages will continue to be logged in C:\Users\dell\AppData\Roaming\JDeveloper\system12.1.2.0.40.66.68\DefaultDomain\servers\DefaultServer\logs\DefaultServer.log.>
<5 avr. 2016 12 h 38 CEST> <Notice> <Log Management> <BEA-170019> <The server log file C:\Users\dell\AppData\Roaming\JDeveloper\system12.1.2.0.40.66.68\DefaultDomain\servers\DefaultServer\logs\DefaultServer.log is opened. All server side log events will be written to this file.>
<5 avr. 2016 12 h 38 CEST> <Error> <EmbeddedLDAP> <BEA-000000> <Error Instantiating 'dc=DefaultDomain': null>
<5 avr. 2016 12 h 38 CEST> <Critical> <EmbeddedLDAP> <BEA-171522> <An error occurred while initializing the embedded LDAP server. The exception that occurred is java.lang.ClassCastException: com.octetstring.vde.backend.BackendRoot cannot be cast to com.octetstring.vde.backend.standard.BackendStandard. This may indicate a problem with the data files for the embedded LDAP server. If the problem is with the data files, and it cannot be corrected, backups of previous versions of the data files exist in C:\Users\dell\AppData\Roaming\JDeveloper\system12.1.2.0.40.66.68\DefaultDomain\servers\DefaultServer\data\ldap\backup.>
<5 avr. 2016 12 h 38 CEST> <Critical> <WebLogicServer> <BEA-000362> <Server failed. Reason:

There are 1 nested errors:

java.lang.ClassCastException: com.octetstring.vde.backend.BackendRoot cannot be cast to com.octetstring.vde.backend.standard.BackendStandard
at weblogic.ldap.EmbeddedLDAP.start(EmbeddedLDAP.java:303)
at weblogic.t3.srvr.SubsystemRequest.run(SubsystemRequest.java:64)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:295)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:254)

>
<5 avr. 2016 12 h 38 CEST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FAILED.>
<5 avr. 2016 12 h 38 CEST> <Error> <WebLogicServer> <BEA-000383> <A critical service failed. The server will shut itself down.>
<5 avr. 2016 12 h 38 CEST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FORCE_SHUTTING_DOWN.>
Stopping Derby server...
Derby server stopped.
Process exited.



MERCI DE M'AIDER