Standalone web app 7.9: Jackson NoSuchMethodError exception on startup

[Andrew_Henderson]

Hi, I have followed the instructions on this page to setup a standalone web application:

https://docs.camunda.org/manual/7.9/installation/standalone-webapplication/

and downloaded: https://camunda.org/release/camunda-bpm/tomcat/7.9/camunda-webapp-tomcat-standalone-7.9.0.war

On startup I randomly get NoSuchMethodError exceptions related to Jackson libraries. i.e:

19-Sep-2018 08:08:48.364 SEVERE [http-nio-8080-exec-9] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [Engine Api] in context with path [/camunda] threw exception [Servlet execution threw an exception] with root cause
 java.lang.NoSuchMethodError: com.fasterxml.jackson.core.JsonGenerator.writeStartObject(Ljava/lang/Object;)V
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:151)
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145)
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107)
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:400)
	at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1392)
	at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913)
	at com.fasterxml.jackson.jaxrs.base.ProviderBase.writeTo(ProviderBase.java:635)
	at org.jboss.resteasy.core.interception.MessageBodyWriterContextImpl.proceed(MessageBodyWriterContextImpl.java:117)
	at org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor.write(GZIPEncodingInterceptor.java:104)
	at org.jboss.resteasy.core.interception.MessageBodyWriterContextImpl.proceed(MessageBodyWriterContextImpl.java:123)
	at org.jboss.resteasy.core.ServerResponse.writeTo(ServerResponse.java:250)
	at org.jboss.resteasy.core.SynchronousDispatcher.writeJaxrsResponse(SynchronousDispatcher.java:602)
	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:528)
	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:126)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

When looking in the webapps/camunda/WEB-INF/lib/ directory I see that there are multiple versions of the Jackson jars:

-rw-r--r--    1 root     root         46968 Sep 13 14:46 jackson-annotations-2.6.0.jar
-rw-r--r--    1 root     root         66519 Sep 13 14:46 jackson-annotations-2.9.0.jar
-rw-r--r--    1 root     root        258875 Sep 13 14:46 jackson-core-2.6.3.jar
-rw-r--r--    1 root     root        321590 Sep 13 14:46 jackson-core-2.9.5.jar
-rw-r--r--    1 root     root       1170801 Sep 13 14:46 jackson-databind-2.6.3.jar
-rw-r--r--    1 root     root       1342410 Sep 13 14:46 jackson-databind-2.9.5.jar

The older versions of these jars don’t have the methods. Why are there two versions? How do we resolve this issue?

thanks,
Andrew

[Andrew_Henderson]

This seems to hint at the problem:

https://docs.camunda.org/manual/7.9/update/minor/78-to-79/#jackson-version-update

but says it should be backward compatible. The spin version is 1.5.1. For now I’m just going to delete the older versions of the libraries.

[thorben]

@Andrew_Henderson

For now I’m just going to delete the older versions of the libraries.

This is the solution. This looks indeed like a bug with the standalone application artifact. It should not include the same Jackson artifact in multiple versions. I have raise a bug ticket: https://app.camunda.com/jira/browse/CAM-9368. Thanks for reporting this.

Cheers,
Thorben

[andrewh]

Hi thorben, I tried deleting the older versions of the Jackson libraries, but then the web app didn’t work. this path returned a 500: https://myhost/camunda/api/engine/engine/

This is in the localhost log:

26-Sep-2018 10:05:42.940 SEVERE [http-nio-8080-exec-10] org.apache.catalina.core.ApplicationContext.log StandardWrapper.Throwable
 java.lang.NoClassDefFoundError: com/fasterxml/jackson/jaxrs/base/ProviderBase
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2529)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:872)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1321)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at org.camunda.bpm.admin.impl.web.AdminApplication.getClasses(AdminApplication.java:42)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.jaxrs.base.ProviderBase
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1352)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	... 34 more

26-Sep-2018 10:05:42.941 SEVERE [http-nio-8080-exec-10] org.apache.catalina.core.StandardWrapperValve.invoke Allocate exception for servlet Admin Api
 java.lang.ClassNotFoundException: com.fasterxml.jackson.jaxrs.base.ProviderBase
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1352)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2529)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:872)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1321)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at org.camunda.bpm.admin.impl.web.AdminApplication.getClasses(AdminApplication.java:42)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

26-Sep-2018 10:05:42.943 SEVERE [http-nio-8080-exec-9] org.apache.catalina.core.ApplicationContext.log StandardWrapper.Throwable
 java.lang.NoClassDefFoundError: com/fasterxml/jackson/jaxrs/base/ProviderBase
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2529)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:872)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1321)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at org.camunda.bpm.engine.rest.impl.CamundaRestResources.<clinit>(CamundaRestResources.java:44)
	at org.camunda.bpm.webapp.impl.engine.EngineRestApplication.getClasses(EngineRestApplication.java:38)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.jaxrs.base.ProviderBase
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1352)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	... 35 more

26-Sep-2018 10:05:42.943 SEVERE [http-nio-8080-exec-9] org.apache.catalina.core.StandardWrapperValve.invoke Allocate exception for servlet Engine Api
 java.lang.ClassNotFoundException: com.fasterxml.jackson.jaxrs.base.ProviderBase
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1352)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2529)
	at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:872)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1321)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1180)
	at org.camunda.bpm.engine.rest.impl.CamundaRestResources.<clinit>(CamundaRestResources.java:44)
	at org.camunda.bpm.webapp.impl.engine.EngineRestApplication.getClasses(EngineRestApplication.java:38)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

26-Sep-2018 10:05:48.890 SEVERE [http-nio-8080-exec-10] org.apache.catalina.core.ApplicationContext.log StandardWrapper.Throwable
 java.lang.NoClassDefFoundError: Could not initialize class org.camunda.bpm.engine.rest.impl.CamundaRestResources
	at org.camunda.bpm.webapp.impl.engine.EngineRestApplication.getClasses(EngineRestApplication.java:38)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

26-Sep-2018 10:05:48.890 SEVERE [http-nio-8080-exec-10] org.apache.catalina.core.StandardWrapperValve.invoke Allocate exception for servlet Engine Api
 java.lang.NoClassDefFoundError: Could not initialize class org.camunda.bpm.engine.rest.impl.CamundaRestResources
	at org.camunda.bpm.webapp.impl.engine.EngineRestApplication.getClasses(EngineRestApplication.java:38)
	at org.jboss.resteasy.spi.ResteasyDeployment.processApplication(ResteasyDeployment.java:456)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:302)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:233)
	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.init(ServletContainerDispatcher.java:67)
	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.init(HttpServletDispatcher.java:36)
	at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1188)
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1132)
	at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:811)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.ha.session.JvmRouteBinderValve.invoke(JvmRouteBinderValve.java:181)
	at org.apache.catalina.ha.tcp.ReplicationValve.invoke(ReplicationValve.java:318)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

[thorben]

The problem with duplicate versions has been resolved in the fresh 7.10.0-alpha4, which you can find here: https://app.camunda.com/nexus/content/groups/public/org/camunda/bpm/webapp/camunda-webapp-tomcat-standalone/7.10.0-alpha4/camunda-webapp-tomcat-standalone-7.10.0-alpha4.war