title: NGINX (Operation not permitted) while reading upstream
body: <p>I have NGINX working as a cache engine and can confirm that pages are being cached as well as being served from the cache. But the error logs are getting filled with this error:</p>
  
  <blockquote>
    <p>2018/01/19 15:47:19 [crit] 107040#107040: *26 chmod()
    "/etc/nginx/cache/nginx3/c0/1d/61/ddd044c02503927401358a6d72611dc0.0000000007"
    failed (1: Operation not permitted) while reading upstream, client:
    xx.xx.xx.xx, server: *.---.com, request: "GET /support/applications/
    HTTP/1.1", upstream: "<a href="http://xx.xx.xx.xx:80/support/applications/" rel="nofollow noreferrer">http://xx.xx.xx.xx:80/support/applications/</a>",
    host: "---.com"</p>
  </blockquote>
  
  <p>I'm not really sure what the source of this error could be since NGINX is working. Are these errors that can be safely ignored?</p>