Postgis Plugin: ERROR: column "z_order" does not exist - Using Kosmtik with OSM Bright

I am trying to create a customized map style with CartoCSS.

Originally I was using Kosmtik with the default openstreetmap-carto style, following this tutorial. I was able to set it up and change some styles. I decided to switch to OSM Bright since it is much more lightweight than openstreetmap-carto and a better starting point for creating a custom style.

After setting up OSM Bright, when I launch kosmtik, I get the following error:

Trace
    at ProjectServer.raise (/home/renderaccount/src/kosmtik/src/back/ProjectServer.js:267:13)
    at /home/renderaccount/src/kosmtik/src/back/ProjectServer.js:81:30
    at /home/renderaccount/src/kosmtik/node_modules/generic-pool/lib/generic-pool.js:283:11
    at loaded (/home/renderaccount/src/kosmtik/node_modules/mapnik-pool/index.js:23:37)
Postgis Plugin: ERROR:  column "z_order" does not exist
LINE 1: SELECT * FROM ( SELECT way, place AS type, name, z_order, po...
                                                         ^
in executeQuery Full sql was: 'SELECT * FROM ( SELECT way, place AS type, name, z_order, population
  FROM planet_osm_point
  WHERE place in ('country', 'state', 'city', 'town', 'village', 'hamlet', 'suburb', 'neighbourhood', 'locality')
  ORDER BY population DESC NULLS LAST
) AS data LIMIT 0'
  encountered during parsing of layer 'place' in Layer

I'm not sure why z_order does not exist. Again, I followed this tutorial by switch2osm to initially set up my tile server.

What should I do to solve this problem?