A plugin blocks or corrupts responses from the WordPress REST API.
Plugin Breaks REST API
Key Points: The REST API fails, preventing block editor, app connections, or plugin features from working.
Gutenberg won’t load, the block editor spins endlessly, or mobile apps can’t connect — often, a plugin has hijacked or broken the REST API responses.
📉 Why It Happens
- Plugin outputs HTML or whitespace in REST responses
- Unauthorized REST routes or incorrect permissions
- Plugin modifies
rest_pre_dispatchwithout fallbacks
🛠️ Diagnostic Steps
- Visit
/wp-json/and look for PHP warnings or output before the JSON - Temporarily disable plugins to find the offender
- Use browser DevTools Network tab to inspect failing REST calls
✅ Fix Approach
Good plugins respect the REST API spec — avoid those that inject output or disable access without clear fallback logic.