Rudder

I have the following error at the start of rudder-jetty on debian 9

2018-01-17 13:18:50.204:WARN:oejx.XmlConfiguration:main: 
java.security.PrivilegedActionException: java.io.IOException: Cannot write log directory /opt/rudder/etc/rudder-jetty-base/var/log/rudder/webapp
        at java.security.AccessController.doPrivileged(Native Method)
        at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1507)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.eclipse.jetty.start.Main.invokeMain(Main.java:221)
        at org.eclipse.jetty.start.Main.start(Main.java:506)
        at org.eclipse.jetty.start.Main.main(Main.java:78)
Caused by: 
java.io.IOException: Cannot write log directory /opt/rudder/etc/rudder-jetty-base/var/log/rudder/webapp
        at org.eclipse.jetty.util.RolloverFileOutputStream.setFile(RolloverFileOutputStream.java:248)
        at org.eclipse.jetty.util.RolloverFileOutputStream.<init>(RolloverFileOutputStream.java:188)
        at org.eclipse.jetty.util.RolloverFileOutputStream.<init>(RolloverFileOutputStream.java:143)
        at org.eclipse.jetty.server.NCSARequestLog.doStart(NCSARequestLog.java:228)
        at org.eclipse.jetty.server.AsyncNCSARequestLog.doStart(AsyncNCSARequestLog.java:104)
        at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
        at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
        at org.eclipse.jetty.server.Server.start(Server.java:449)
        at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:113)
        at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:113)
        at org.eclipse.jetty.server.Server.doStart(Server.java:416)
        at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
        at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1584)
        at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1508)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1507)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.eclipse.jetty.start.Main.invokeMain(Main.java:221)
        at org.eclipse.jetty.start.Main.start(Main.java:506)
        at org.eclipse.jetty.start.Main.main(Main.java:78)

path /opt/rudder/etc/rudder-jetty-base/var/log/rudder/webapp is invalid