Machine learning features unavailable after rolling upgrade

This problem occurs after you upgrade all of the nodes in your cluster to 5.6.1 by using rolling upgrades. When you try to use X-Pack machine learning features for the first time, all attempts fail, though GET _xpack and GET _xpack/usage indicate that X-Pack is enabled.

Symptoms:

  • Errors when you click Machine Learning in Kibana. For example: Jobs list could not be created and An internal server error occurred.
  • Null pointer and remote transport exceptions when you run machine learning APIs such as GET _xpack/ml/anomaly_detectors and GET _xpack/ml/datafeeds.
  • Errors in the log files on the master nodes. For example: unable to install ml metadata upon startup

Resolution:

After you upgrade all master-eligible nodes to Elasticsearch 5.6.1 and X-Pack 5.6.1, restart the current master node, which triggers the X-Pack machine learning features to re-initialize.

For more information, see Rolling upgrades.