What is “XMLReader::open() failed to open stream: HTTP request failed”?
Question: What is "XMLReader::open() failed to open stream: HTTP request failed"?
Answer: It sounds like the server where your website is hosted is misconfigured, or does not allow WordPress to connect to itself. The Comet Cache Auto-Cache Engine needs to read your XML Sitemap (e.g.,
http://example.com/sitemap.xml) so that it can find all the pages on your site and cache them.
If Comet Cache cannot read the URL to your XML Sitemap, then the Auto-Cache Engine will be unable to function properly. As a result, you may see an error like the following in your error log whenever the Auto-Cache Engine runs:
[06-Mar-2015 12:03:59 UTC] PHP Warning: XMLReader::open(http://example.com/sitemap.xml): failed to open stream: HTTP request failed! in /home/example/public_html/wp-content/plugins/comet-cache-pro/includes/auto-cache.php on line 233
Please contact your web hosting company and ask them to to help you troubleshoot this server issue. Let them know you're running a WordPress plugin called Comet Cache that needs to read your XML Sitemap URL using an HTTP request.