**1. Describe your incident:
**
A cluster consisting of one leader and two non-leaders.
An upgrade was performed on one of the slaves, and the container logs show a login error:
ERROR: org.apache.shiro.session.mgt.ExecutorServiceSessionValidationScheduler - Error while validating the session
java.lang.RuntimeException: IOException encountered while parsing
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "attributes" (class org.graylog2.security.sessions.AutoValue_SessionDTO$Builder), not marked as ignorable (12 known properties: "timeout", "session_id", "expired", "host", "start_timestamp", "_id", "authenticated", "authentication_realm", "user_name", "last_access_time", "user_id", "auth_context")
at [Source: (String); byte offset: #UNKNOWN] (through reference chain: org.graylog2.security.sessions.AutoValue_SessionDTO$Builder["attributes"])
Sessions in two formats are stored in db.sessions. What is the correct way to clean them (if that is the cause)? Or what should the update procedure be in that case?.