I get this exception when i try to start my bitbucket server.

Likely root cause: java.lang.ClassNotFoundException: java.util.Base64
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.net.FactoryURLClassLoader.loadClass(URLClassLoader.java:789)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at com.atlassian.elasticsearch.buckler.BasicAuth.encodeCredentials(BasicAuth.java:22)
at com.atlassian.elasticsearch.buckler.config.AuthConfig.<init>(AuthConfig.java:25)
at com.atlassian.elasticsearch.buckler.config.BucklerConfig.<init>(BucklerConfig.java:55)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at <<<guice>>>
at org.elasticsearch.node.Node.<init>(Node.java:213)
at org.elasticsearch.node.Node.<init>(Node.java:140)
at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:143)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:178)
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:270)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)