I have just been dealing with the same issue after upgrading Splunk to version 7.01. I found the issue was resolved by simply upgrading the oracle database driver. I was using the old driver ojdbc6.jar, and after upgrading this to ojdbc7.jar everything worked fine again.
For instructions on how to install a new database driver and links to download the drivers see the below documentation page:
http://docs.splunk.com/Documentation/DBX/3.1.1/DeployDBX/Installdatabasedrivers
,I have just been dealing with the same problem after upgrading to Splunk 7.01. I found it was caused by the fact that I had the Oracle driver ojdbc6.jar. Once I updated this to ojdbc7.jar everything started working again.
Instructions for installing a new driver and links to where they can be downloaded can be found here:
http://docs.splunk.com/Documentation/DBX/3.1.1/DeployDBX/Installdatabasedrivers
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