I've been using wp-json steadily for a couple years now on a headless CMS project and had no problem getting valid JSON back. I set the website to auto-update all themes, plugins, and WP version. I also added some extra plugins to enhance the wp-json:

  • WP Rest Api V2 Multiple PostTypes
  • REST API Helper
  • Custom Post Types

Today, we started getting invalid JSON back with an "lea" prefix string on the beginning of the JSON for some unknown reason, creating invalid JSON. When I remove this "lea" prefix at the beginning of the JSON, the website works normal again.

Where might I look to see where this "lea" is being added?

1 Answer 1


I found it. There's a bug in the TotalPress.org Custom Post Types plugin in the file:


At the top of the file, you will see the mistake:


When I remove the lea, the problem goes away. I'm contacting the plugin developer to let them know. Plugin version was 3.0.12.

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