To fix broken XHR (XMLHttpRequest) resources that may be preventing search bots from successfully rendering your site, you should follow these steps:
Identify the Broken Resources:
Start by using tools like Google Search Console for error reports, and crawlers like Screaming Frog or Sitebulb to detect broken XHR links. These tools can identify resources that are failing to load.
Understand the Resource Context:
Analyze the role of the broken XHR requests on your site. Determine if they are critical for rendering main content or if they affect auxiliary features. Ensure critical resources are served to bots effectively.
Check Server Logs:
Study your server logs to pinpoint any server-side issues such as 404 (Not Found) or 500 (Server Error) responses for these resources. These logs can provide insights into why resources are not being served properly.
Correct URL Issues:
If the XHR resource URLs are incorrect, missing, or malformed, update them so that they correctly point to the existing resources. Ensure that your paths are absolute URLs and not relative where necessary.
Implement Graceful Fallbacks:
On the client side, have fallback mechanisms in place for when XHR requests fail. This might involve displaying alternative content or requesting the data anew after a delay.
Check and Set Proper CORS Policies:
Cross-Origin Resource Sharing (CORS) issues can prevent resources from loading correctly. Check that your servers allow these resources to be accessed by setting the appropriate headers.
Cache Management:
Leverage HTTP caching appropriately to reduce the load on your server and ensure that resources are quickly available. Ensure that cache headers are correctly set to allow resources to be reused effectively.
Render Critical Data Server-Side:
For critical data needed at the first render, consider server-side rendering (SSR) or static generation (in applicable frameworks) so that search engines can index the HTML directly without relying on executing JavaScript.
Testing and Validation:
After applying fixes, re-test using rendering tools like the Google Search Console Fetch and Render tool to ensure that search bots can successfully access and render the content.

Properly maintaining and troubleshooting XHR resources involves a continuous process of monitoring and optimizing your web resources to ensure seamless accessibility and rendering for search bots, facilitating better indexability and ranking in search engine results.