I came across strange behaviour while trying to understand why my WordPress admin is so slow. It came to my attention that one of the js file was not accessible and Cloudflare was returning Error 522.
So first thing I did is to make sure that file actually exists and cleared all cache and by providing full url to specific file http and https.
The result was the same, error 522.
So I tried different browser, Opera, Firefox, Explorer all off them received same response.
Next thing I did was trying to access this file from other region via VPN, and surprisingly resource is available.
So it seems like resource
/wp-includes/js/dist/vendor/wp-polyfill.min.js?ver=7.0.0 was permanently cached on one of the CDNs in KIEV to be precise. All other CDN show resource correctly. If I change the query string let’s say to 7.0.1 everything works.
Did any one came across that issue and knows how to fix it?