HTTP 500 Errors From WLS Within the Apache Proxy Log for a HTTP Proxy Service

Using Oracle Service Bus user faces HTTP 500 internal server errors intermittently in access.log for OSB http proxy requests.

By enabling pipeline debug getting the following exceptions :

<[ACTIVE] ExecuteThread: '8' for queue: 'weblogic.kernel.Default (self-tuning)'> <> <> <> <1294866198373> error handler
com.bea.wli.sb.pipeline.PipelineException: OSB Assign action failed updating variable "body": Could not load the translet class 'transformXMLtoICONHTML'.
at stages.transform.runtime.AssignRuntimeStep.processMessage(AssignRuntimeStep.java:66)

Cause

This issue is caused by a known apache XLSTC issue. For details see https://issues.apache.org/jira/browse/XALANJ-1549 .

Solution

To fix this, use another xslt library by using the standard system property i.e.

javax.xml.transform.TransformerFactory.

For example, to use the weblogic implementation, you can specify this as a system property in setdomainenv script:
-Djavax.xml.transform.TransformerFactory=weblogic.apache.xalan.processor.TransformerFactoryImpl