The preview could not be loaded 📝 WordPress

Elementor: The preview could not be loaded / Server Error 500 / Preview Debug

Elementor’s editor couldn’t load the page preview in its iframe — PHP errors, memory limits, mixed URLs, or plugin conflicts.

Seen on: WordPress

Meaning

The preview is a frontend request inside the editor. Fatal errors, low memory, siteurl/home mismatches (http vs https), X-Frame-Options/CSP blocking iframes, or caching/optimisation plugins break it.

Common causes

  • PHP memory too low (Elementor recommends 256M+)
  • PHP fatal error from a plugin/theme
  • siteurl/home mismatch or mixed content
  • Security headers blocking same-origin iframes
  • Cache/optimisation plugins interfering

⚡ Quick fix

  1. Raise WP_MEMORY_LIMIT
  2. Enable WP_DEBUG_LOG and read errors while loading the editor
  3. Check Elementor → System Info and Preview Debug; disable conflicting plugins

Detailed fix by platform

WordPress

  1. php
    define('WP_MEMORY_LIMIT', '512M');
define('WP_DEBUG', true); define('WP_DEBUG_LOG', true); define('WP_DEBUG_DISPLAY', false);

How to diagnose

  1. Log — debug.log errors
  2. URLs — siteurl/home
  3. Headers — X-Frame-Options/CSP

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

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