Unable to load current conversations from the associated request on Tomcat

Container: apache-tomcat-7.0.47
Weld version: 2.1.2

Weld is started over the web.xml with the listener: org.jboss.weld.environment.servlet.Listener

We deployed a WAR file with a PrimeFaces user interface and made many many automatic gui tests. After updating to this weld version and switching to the tomcat 7 we get this exception after a random time...
The exception occurs in differnt tests on different times, it is not possible to describe the bug to reproduce it...

After the exception occurs, the web app is no more useable or have undesirable side effects

java.lang.IllegalStateException: WELD-000341: Unable to load current conversations from the associated request, something went badly wrong when associate() was called
at org.jboss.weld.context.AbstractConversationContext.getCurrentConversation(AbstractConversationContext.java:434)
at org.jboss.weld.servlet.ConversationContextActivator.deactivateConversationContext(ConversationContextActivator.java:145)
at org.jboss.weld.servlet.HttpContextLifecycle.requestDestroyed(HttpContextLifecycle.java:217)
at org.jboss.weld.servlet.WeldInitialListener.requestDestroyed(WeldInitialListener.java:136)
at org.jboss.weld.servlet.api.helpers.ForwardingServletListener.requestDestroyed(ForwardingServletListener.java:38)
at org.apache.catalina.core.StandardContext.fireRequestDestroyEvent(StandardContext.java:6137)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:207)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:679)