Overview

When using the output from Drupal’s JSON:API in a separate application, a CORS error occurred. Here, I explain how to resolve the CORS error.

Solution

Copy the following file:

/web/sites/default/default.services.yml

cp /web/sites/default/default.services.yml /web/sites/default/services.yml

Then, set enabled to true in cors.config:

# Configure Cross-Site HTTP requests (CORS).
  # Read https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
  # for more information about the topic in general.
  # Note: By default the configuration is disabled.
  cors.config:
    enabled: false # Change this to true!
    # Specify allowed headers, like 'x-allowed-header'.
    allowedHeaders: []

As a result, the CORS error was resolved.

Summary

I hope this serves as a useful reference for anyone experiencing a similar issue.