How to fix The error “Updating failed. The response is not a valid JSON response.” in WordPress

The error “Updating failed. The response is not a valid JSON response.” in WordPress usually means the editor cannot communicate correctly with your server. This is very common and usually caused by permalinks, plugins, security rules, or server configuration.

Follow these fixes in order (most cases solved in Step 1 or 2).

Refresh Permalinks (Most Common Fix)

1. Go to Dashboard → Settings → Permalinks
2. Click Save Changes (without changing anything)

This rebuilds WordPress rewrite rules and fixes many JSON errors.

Check Site URL (HTTP vs HTTPS)

Sometimes the editor sends requests to a different URL.

Go to:

Settings → General

Make sure both are the same:

WordPress Address (URL)
Site Address (URL)

Example (correct):

https://moralstory.in
https://moralstory.in

NOT:

http://moralstory.in
https://moralstory.in

Disable Security / Cache Plugins

Temporarily disable plugins like:

• Wordfence
• LiteSpeed Cache
• WP Rocket
• All In One Security

Then try updating the post again.

Check REST API

Open this in browser:

https://moralstory.in/wp-json/

If it shows JSON text → REST API is working.

If it shows 403 / error / blank page → hosting or security blocking it.

Fix .htaccess

Open .htaccess in root and replace with:

# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
# END WordPress

Increase PHP Limits

Add in wp-config.php

define('WP_MEMORY_LIMIT', '256M');

Cloudflare / Firewall Issue

If you use:

• Cloudflare
• hosting firewall

Disable Bot protection / ModSecurity temporarily.

Console Error Check

Press:

F12 → Console

If you see:

403
500
rest_cookie_invalid_nonce

tell me the error.

Quickest Fix (Usually Works)

Do these 3 steps first:

1. Settings → Permalinks → Save
2. Clear cache plugin
3. Check https vs http