This post explains how to set custom Elasticsearch configuration within Warden to fix the Fielddata access on the _id field is disallowed error with Elasticsearch 8. This is a follow on from a earlier post explaining common ES8 configuration issues with Magento.

The error was are going to fix related to ES8 changing the default values for _id fielddata

Fielddata access on the _id field is disallowed, you can re-enable it by updating the dynamic cluster setting: indices.id_field_data.enabled"

The Solution

Within your project root create a file at .warden/warden-env.yml with the following content

version: "3.5"
      - indices.id_field_data.enabled=true

Now restart your warden environment warden env restart, followed by a reindex warden shell -c "php bin/magento index:reindex; php bin/magento c:f" and voila, you should now have a catalog again!