https://sourceforge.net/tracker/?func=detail&aid=2832968&group_id=176962&atid=955896 ( User context lost )

- session context not clean up properly

zkwebui/WEB-INF/src/org/adempiere/webui/session/SessionContextListener.java

@@ -187,6 +187,7 @@ public class SessionContextListener implements ExecutionInit,
     	if (ctx != null && serverContext != null 
     		&& ctx.getProperty(SERVLET_SESSION_ID).equals(serverContext.getProperty(SERVLET_SESSION_ID)))
     	{
+    		ctx.clear();
     		ctx.putAll(serverContext);
     	}