We have WAS 6.0 (I know) .2.43 ND running in multiple regions. Our Dev-B region runs fine, but Dev-C throws a java exception when we make web-calls (at least this is what the developer tells me)...Same code in both regions and I checked the obvious suspects (Global security, SSL ciphers etc) and they all seem to match. Here's the stack trace from SystemErr: [8/1/12 4:02:31:758 EDT] 0000005c ServletWrappe E SRVE0068E: Could not invoke the service() method on servlet action. Exception thrown : java.lang.NoClassDefFoundError at javax.crypto.Mac.getInstance(DashoA12275) at net.oauth.signature.HMAC_SHA1.computeSignature(HMAC_SHA1.java:73) at net.oauth.signature.HMAC_SHA1.getSignature(HMAC_SHA1.java:39) at net.oauth.signature.OAuthSignatureMethod.getSignature(OAuthSignatureMethod.java:83) at net.oauth.signature.OAuthSignatureMethod.sign(OAuthSignatureMethod.java:54) at com.harcourt.hsp.utils.LTIUtil.generateSignature(LTIUtil.java:62) at com.harcourt.hsp.web.struts.lti.action.BaseLTIAction.generateSignature(BaseLTIAction.java:238) at com.harcourt.hsp.web.struts.lti.action.BaseLTIAction.execute(BaseLTIAction.java:96) at org.springframework.web.struts.DelegatingActionProxy.execute(DelegatingActionProxy.java:106) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194) at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) at javax.servlet.http.HttpServlet.service(HttpServlet.java:743) at javax.servlet.http.HttpServlet.service(HttpServlet.java:856) at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1796) at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:887) at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90) at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1937) at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:130) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:434) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:373) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:253) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminaters(NewConnectionInitialReadCallback.java:207) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:109) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java:566) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java:619) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java:952) at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java:1039) at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1498) at javax.crypto.Mac.getInstance(DashoA12275) at net.oauth.signature.HMAC_SHA1.computeSignature(HMAC_SHA1.java:73) at net.oauth.signature.HMAC_SHA1.getSignature(HMAC_SHA1.java:39) at net.oauth.signature.OAuthSignatureMethod.getSignature(OAuthSignatureMethod.java:83) at net.oauth.signature.OAuthSignatureMethod.sign(OAuthSignatureMethod.java:54) at com.harcourt.hsp.utils.LTIUtil.generateSignature(LTIUtil.java:62) at com.harcourt.hsp.web.struts.lti.action.BaseLTIAction.generateSignature(BaseLTIAction.java:238) at com.harcourt.hsp.web.struts.lti.action.BaseLTIAction.execute(BaseLTIAction.java:96) at org.springframework.web.struts.DelegatingActionProxy.execute(DelegatingActionProxy.java:106) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194) at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) at javax.servlet.http.HttpServlet.service(HttpServlet.java:743) at javax.servlet.http.HttpServlet.service(HttpServlet.java:856) at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1796) at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:887) at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90) at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1937) at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:130) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:434) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:373) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:253) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminaters(NewConnectionInitialReadCallback.java:207) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:109) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java:566) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java:619) at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java:952) at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java:1039) at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1498) Thanks for your help. I'm sure it's a config that I'm missing.