🔍 Overview

When activating Bing IndexNow through OTTO on a WordPress site, some customers encounter an "Index Now key not found" error (HTTP 400). This happens even when the Search Atlas WordPress plugin is correctly installed and a CMS Connector connection is active. This article explains why the error occurs and how to resolve it.

⚠️ Why This Error Happens

Bing's IndexNow verification process requires your site to serve a plain-text key file at a specific URL. The error is triggered when Bing cannot access that file. Common causes include:

• Your server uses nginx and returns a 403 Forbidden response for .txt files in the site root.
• A server-level rule blocks direct access to root-level text files.
• A caching layer or CDN intercepts the request before the key file can be served.
• The key file was not yet written to disk at the moment Bing attempted verification.
• A previous plugin version did not include the virtual serving or keyLocation fallback logic now required for certain hosting environments.

✅ Step-by-Step Fix

1. Update the Search Atlas WordPress plugin. Go to your WordPress dashboard, navigate to Plugins → Installed Plugins, and check for an available update to the Search Atlas plugin. Install the latest version — it includes a fix that serves the IndexNow key file virtually and adds a keyLocation fallback for nginx hosts that previously returned 403 errors.
2. Verify the key file is accessible. After updating, open a browser and go to https://yourdomain.com/<your-indexnow-key>.txt. Replace <your-indexnow-key> with the actual key shown in OTTO. The page should return a plain-text response containing only the key string. If you see a 403 or 404, proceed to the next steps.
3. Check nginx or .htaccess rules. If your host uses nginx, ask your hosting provider to confirm that .txt files in the web root are not blocked. If your host uses Apache, open your .htaccess file and look for any Deny or FilesMatch rules that may block .txt access.
4. Purge your cache. If you use a caching plugin (WP Rocket, W3 Total Cache, LiteSpeed Cache, etc.) or a CDN (Cloudflare, etc.), purge all cached files. Cached 404 or 403 responses can prevent Bing from seeing the key file even after the plugin is updated.
5. Retry activation in OTTO. In the Search Atlas platform, go to OTTO SEO (left sidebar) and open your site's OTTO dashboard. Navigate to Indexing → Bing IndexNow and click Activate (or Retry) to trigger a fresh key verification.

🔎 Confirm the Fix Worked

After retrying activation, OTTO will show a green active status next to Bing IndexNow when verification succeeds. If the status remains red or the error persists, use the troubleshooting checklist below before contacting support.

📋 Troubleshooting Checklist

• Plugin is updated to the latest Search Atlas version.
• Key file URL returns HTTP 200 with plain-text key content in a browser.
• No nginx location block or .htaccess rule blocks root .txt files.
• Site cache and CDN cache have been fully purged.
• WordPress site is publicly accessible (not behind basic auth or maintenance mode).
• OTTO activation was retried after completing all steps above.

💬 Still Seeing the Error?

If you have completed every step above and the "Index Now key not found" error still appears, our team can investigate your specific server configuration. If you need further assistance, open the chat widget in the bottom-right corner of the platform and type human teammate to be connected with a member of our team.