The Cloudflare cdn-cgi/rum? 404 error is a common issue that website owners encounter when using Cloudflare’s Web Analytics and Real User Monitoring (RUM) features. This error occurs when your website attempts to access the /cdn-cgi/rum? endpoint but receives a HTTP 404 Not Found response instead of the expected data.

Understanding the cdn-cgi/rum Error

This HTTP 404 error specifically relates to Real User Monitoring functionality that collects visitor performance metrics to analyse website speed and user experience. When RUM is enabled in Cloudflare Web Analytics, a JavaScript snippet is automatically injected into your site that makes POST requests to the /cdn-cgi/rum? endpoint.

This endpoint is managed entirely by Cloudflare and serves various purposes across different Cloudflare products, including bot protection, image transformations, email obfuscation, and analytics collection.

Why This Error Occurs

Several factors can trigger this issue:

• Real User Monitoring is enabled but not properly configured
• Cloudflare middleware conflicts or temporary service issues
• DNS proxy configuration problems
• Cached responses serving outdated endpoint information

The error typically manifests as JavaScript console errors or failed network requests visible in browser developer tools, though it won’t appear in your origin server logs since the request is handled by Cloudflare’s middleware.

Complete Resolution Options

Option 1: Disable Real User Monitoring (Recommended)

The most straightforward solution to resolve the the cdn-cgi/rum? error is disabling RUM entirely:

1. Log into your Cloudflare dashboard
2. Navigate to Analytics & Logs > Web Analytics
3. Select Manage Site for the affected hostname
4. Click Disable to remove RUM tracking
5. Clear your website cache to ensure changes take effect

Option 2: Block cdn-cgi in robots.txt

Add comprehensive crawler blocking to prevent search engines from encountering these errors:

User-agent: *
Disallow: /cdn-cgi/

This approach resolves Google Search Console errors related to the Cloudflare cdn-cgi/rum? 404 error within approximately 48 hours without affecting your site’s organic performance.

Option 3: Configure Web Analytics Properly

If you need RUM functionality, ensure proper configuration:

1. Disable existing RUM setup completely
2. Wait 24-48 hours for changes to propagate
3. Re-enable Web Analytics with fresh configuration
4. Verify the JavaScript snippet loads correctly
5. Monitor network requests for successful endpoint responses

Option 4: Exclude from Security Scanners

Prevent false positives in security scanning tools:

1. Add /cdn-cgi/ to your scanner’s exclusion list
2. Configure monitoring tools to ignore 404 responses from cdn-cgi endpoints
3. Focus security scanning on your actual website content and functionality

Impact on Website Performance

The Cloudflare cdn-cgi/rum? issue does not negatively impact your organic search performance or website rankings. Google and other search engines understand that cdn-cgi endpoints contain no valuable content for indexing purposes.

However, the error can create unnecessary noise in monitoring tools and may consume browser resources through failed network requests. Resolving the issue improves overall site monitoring clarity and reduces console errors.

Prevention and Monitoring

To prevent future occurrences:

• Regularly review your Cloudflare Analytics settings
• Monitor Google Search Console for crawl errors
• Implement proper robots.txt exclusions as a preventative measure
• Test Web Analytics functionality thoroughly after any Cloudflare configuration changes

Most websites can safely disable RUM without losing valuable analytics data, as alternative monitoring solutions often provide more comprehensive insights into user behaviour and site performance. Following these resolution steps will eliminate the problem whilst maintaining your website’s functionality and search engine visibility.