One thing I'll note is that I /don't/ get this error when I execute the update via other means.
Perhaps, those other tools (Squirrel, etc.) are not using the special form of Statement.executeUpdate() which requests that the auto-generated keys should be made available, while the Vert.x framework is. https://docs.oracle.com/javase/7/docs/api/java/sql/Statement.html#executeUpdate(java.lang.String,%20int) bryan
