Hi, I had to update a custom distribution that contains a bundle that is using the Spring Framework. Currently the distribution is using Karaf 4.2.1, so Spring Framework 5.0.8.RELEASE_1. After the bump Karaf 4.2.5 will be used and so Spring Framework 5.0.12.RELEASE_1.
While doing the migration I get an CNF exception on startup. === RROR [paxweb-extender-1-thread-1] Exception finalizing HttpContext registration javax.servlet.ServletException: mvc-dispatcher@f974527a==org.springframework.web.servlet.DispatcherServlet,jsp=null,order=1,inst=false at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:691) ~[?:?] at org.eclipse.jetty.servlet.ServletHolder.initialize(ServletHolder.java:427) ~[?:?] at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:760) ~[?:?] at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:374) ~[?:?] at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.startContext(HttpServiceContext.java:414) ~[?:?] at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:847) ~[?:?] at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:287) ~[?:?] at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doStart(HttpServiceContext.java:267) ~[?:?] at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[?:?] at org.ops4j.pax.web.service.jetty.internal.JettyServerImpl$1.start(JettyServerImpl.java:329) ~[?:?] at org.ops4j.pax.web.service.internal.HttpServiceStarted.end(HttpServiceStarted.java:1261) ~[?:?] at org.ops4j.pax.web.service.internal.HttpServiceProxy.end(HttpServiceProxy.java:456) ~[?:?] at org.ops4j.pax.web.extender.war.internal.RegisterWebAppVisitorWC.end(RegisterWebAppVisitorWC.java:405) ~[?:?] at org.ops4j.pax.web.extender.war.internal.model.WebApp.accept(WebApp.java:658) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebAppPublisher$WebAppDependencyListener.register(WebAppPublisher.java:228) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebAppPublisher$WebAppDependencyListener.addingService(WebAppPublisher.java:173) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebAppPublisher$WebAppDependencyListener.addingService(WebAppPublisher.java:129) ~[?:?] at org.osgi.util.tracker.ServiceTracker$Tracked.customizerAdding(ServiceTracker.java:941) ~[?:?] at org.osgi.util.tracker.ServiceTracker$Tracked.customizerAdding(ServiceTracker.java:870) ~[?:?] at org.osgi.util.tracker.AbstractTracked.trackAdding(AbstractTracked.java:256) ~[?:?] at org.osgi.util.tracker.AbstractTracked.trackInitial(AbstractTracked.java:183) ~[?:?] at org.osgi.util.tracker.ServiceTracker.open(ServiceTracker.java:318) ~[?:?] at org.osgi.util.tracker.ServiceTracker.open(ServiceTracker.java:261) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebAppPublisher.publish(WebAppPublisher.java:98) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebObserver.deploy(WebObserver.java:217) ~[?:?] at org.ops4j.pax.web.extender.war.internal.WebObserver$1.doStart(WebObserver.java:172) ~[?:?] at org.ops4j.pax.web.extender.war.internal.extender.SimpleExtension.start(SimpleExtension.java:59) ~[?:?] at org.ops4j.pax.web.extender.war.internal.extender.AbstractExtender.lambda$createExtension$0(AbstractExtender.java:277) ~[?:?] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:?] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:?] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?] at java.lang.Thread.run(Thread.java:748) [?:?] Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/mvc-dispatcher-servlet.xml]; nested exception is org.springframework.beans.FatalBeanException: Unresolvable class definition for NamespaceHandler class [org.springframework.web.socket.config.WebSocketNamespaceHandler] for namespace [http://www.springframework.org/schema/websocket]; nested exception is java.lang.NoClassDefFoundError: org/springframework/beans/factory/xml/NamespaceHandlerSupport at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:414) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:223) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:194) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) ~[?:?] at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:619) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:520) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:677) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:643) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:691) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:557) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:502) ~[?:?] at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172) ~[?:?] at javax.servlet.GenericServlet.init(GenericServlet.java:244) ~[?:?] at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:670) ~[?:?] ... 34 more Caused by: org.springframework.beans.FatalBeanException: Unresolvable class definition for NamespaceHandler class [org.springframework.web.socket.config.WebSocketNamespaceHandler] for namespace [http://www.springframework.org/schema/websocket]; nested exception is java.lang.NoClassDefFoundError: org/springframework/beans/factory/xml/NamespaceHandlerSupport at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:144) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1361) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1352) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:178) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:148) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:98) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:508) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:223) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:194) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) ~[?:?] at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:619) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:520) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:677) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:643) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:691) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:557) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:502) ~[?:?] at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172) ~[?:?] at javax.servlet.GenericServlet.init(GenericServlet.java:244) ~[?:?] at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:670) ~[?:?] ... 34 more Caused by: java.lang.NoClassDefFoundError: org/springframework/beans/factory/xml/NamespaceHandlerSupport at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?] at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.defineClass(BundleWiringImpl.java:2410) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2194) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1607) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.getClassByDelegation(BundleWiringImpl.java:1414) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.searchImports(BundleWiringImpl.java:1660) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1590) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.apache.felix.framework.Felix.loadBundleClass(Felix.java:1927) ~[?:?] at org.apache.felix.framework.BundleImpl.loadClass(BundleImpl.java:978) ~[?:?] at org.ops4j.pax.swissbox.core.BundleClassLoader.findClass(BundleClassLoader.java:176) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:?] at org.ops4j.pax.swissbox.core.BundleClassLoader.loadClass(BundleClassLoader.java:192) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.springframework.util.ClassUtils.forName(ClassUtils.java:275) ~[?:?] at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:129) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1361) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1352) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:178) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:148) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:98) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:508) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:223) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:194) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) ~[?:?] at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:619) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:520) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:677) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:643) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:691) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:557) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:502) ~[?:?] at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172) ~[?:?] at javax.servlet.GenericServlet.init(GenericServlet.java:244) ~[?:?] at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:670) ~[?:?] ... 34 more Caused by: java.lang.ClassNotFoundException: org.springframework.beans.factory.xml.NamespaceHandlerSupport not found by org.apache.servicemix.bundles.spring-websocket [129] at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1639) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?] at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.defineClass(BundleWiringImpl.java:2410) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2194) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1607) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.getClassByDelegation(BundleWiringImpl.java:1414) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.searchImports(BundleWiringImpl.java:1660) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1590) ~[?:?] at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?] at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.apache.felix.framework.Felix.loadBundleClass(Felix.java:1927) ~[?:?] at org.apache.felix.framework.BundleImpl.loadClass(BundleImpl.java:978) ~[?:?] at org.ops4j.pax.swissbox.core.BundleClassLoader.findClass(BundleClassLoader.java:176) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:?] at org.ops4j.pax.swissbox.core.BundleClassLoader.loadClass(BundleClassLoader.java:192) ~[?:?] at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] at org.springframework.util.ClassUtils.forName(ClassUtils.java:275) ~[?:?] at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:129) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1361) ~[?:?] at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1352) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:178) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:148) ~[?:?] at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:98) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:508) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:392) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336) ~[?:?] at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:223) ~[?:?] at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:194) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) ~[?:?] at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) ~[?:?] at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:619) ~[?:?] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:520) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:677) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:643) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:691) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:557) ~[?:?] at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:502) ~[?:?] at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172) ~[?:?] at javax.servlet.GenericServlet.init(GenericServlet.java:244) ~[?:?] at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:670) ~[?:?] ... 34 more === "Caused by: java.lang.ClassNotFoundException: org.springframework.beans.factory.xml.NamespaceHandlerSupport not found by org.apache.servicemix.bundles.spring-websocket [129]" I checked "bundle:headers org.apache.servicemix.bundles.spring-websocket" and the package import section contains === org.springframework.beans.factory.xml;resolution:=optional;version="[5.1.5.RELEASE,5.2)", === The line is "not red", so it should be wired correctly. The UI bundle that is using the Spring Framework also contains that line: === org.springframework.beans.factory.xml;version="[5.0,6)", === for its package imports. I will try to further inspect this error, but perhaps someone already knows what needs to be done... Best regards, Markus