If you see the message "Skipping unexpected null message encountered on store boot", you will need to recreate your JDBC store, because it got corrupted.
You will see a message like this in the weblogic server log:
<Warning> <Messaging> <BEA-282013> <Skipping unexpected null message encountered on store boot, [ sequence=4862 queue=12 name=MyModule!MyQueue state=0 deliveryCount=2 ]>
Steps to fix the issue:
1. Make sure managed server is not running
2. Delete the corrupted JDBC store because messages are corrupted.
See Managing JDBC Store Tables
http://docs.oracle.com/cd/E23943_01/web.1111/e13701/store.htm#i1143431
e.g.:
If you have provided the prefix MY when you created your JDBC store, your table is named MYWLStore, otherwise, it is just named WLStore
To drop the table, you can use the option below or simply drop it using a database tool:
$ echo "drop MYWLStore;"> drop.ddl
$ cd <YourDomain>/bin
$. ./setDomainEnv.sh
**Notice the . before ./
$ java utils.Schema jdbc:weblogic:oracle:DEMO weblogic.jdbc.oci.Driver -u user1 -p foobar -verbose drop.ddl
3. Start managed server. The store table will be recreated when managed server is started
Enjoy!