OK, a bit of digging, led me to this http://support.bea.com/application_content/product_portlets/support_patte.... Going by what is mentioned in that article, i guess, the problem you are having is related to a programming error rather than a classloader issue. Here's the relevant part from that article (you might want to go through that complete article as it recommends some programming techniques to avoid these issues with weblogic driver): anonymous wrote : Since the WebLogic driver uses WebLogic wrapper classes, no typecasting is required when using this driver. If typecasting is used, ClassCastException will be thrown | | The actual exception that occurs is on the line | | os = ((OracleThinBlob)myRegularBlob).getBinaryOutputStream();" | | To resolve this issue, the above code needs to be modified. | Replace | os = ((OracleThinBlob)myRegularBlob).getBinaryOutputStream(); | with | os = myRegularBlob.setBinaryStream(1); | Blob blob = resultset.getBlob("xml"); | if(blob != null) | { | OutputStream outputstream = ((OracleBlob)blob).getBinaryOutputStream(); I guess, this line is causing the ClasscastException. To fix this, i guess a code change will be required. Since you don't have access to the code, you might have to bring this to the notice of your developers. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4128178#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...