Comment 1 for bug 1719506

5.5.57-38.9, 5.6.37-82.2, 5.7.19-17
docker run --rm -it -e MYSQL_ALLOW_EMPTY_PASSWORD=1 --name p55 percona:5.5
apt-get update ; apt-get install -y python3-mysql.connector
mysql -e "INSTALL PLUGIN audit_log SONAME 'audit_log.so';"
python3 << 'EOF'
import mysql.connector
cnx = mysql.connector.connect(database='information_schema', user='root')
cursor = cnx.cursor(prepared=True)
stmt = "SHOW GLOBAL VARIABLES WHERE Variable_name = ?"
cursor.execute(stmt, ("max_allowed_packet",))
cursor.fetchall()
cursor.close()
cnx.close()
EOF

In addition to prepared statements command class is error for Ping:
<AUDIT_RECORD
  NAME="Ping"
  RECORD="7_2017-10-04T04:45:30"
  TIMESTAMP="2017-10-04T04:47:37 UTC"
  COMMAND_CLASS="error"
  CONNECTION_ID="2"
  STATUS="0"
  SQLTEXT=""
  USER="root[root] @ [127.0.0.1]"
  HOST=""
  OS_USER=""
  IP="127.0.0.1"
/>

Andrew, please provide information about your mysql client library (what programming language you are using?)