Caching Issue : HTTP expire header added like this “Expires: Thu, 19 Nov 1981”

This is some example with Voucherpress enabled and disabled using curl -I https://www.spazionapoli.it

Enabled :

HTTP/1.1 200 OK
Server: nginx
Content-Type: text/html; charset=UTF-8
Vary: Accept-Encoding
X-Powered-By: PHP/5.6.26
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Link: <https://www.spazionapoli.it/wp-json/&gt;; rel=”https://api.w.org/&#8221;
Link: <https://www.spazionapoli.it/&gt;; rel=shortlink
Last-Modified: Sat, 15 Oct 2016 13:16:47 GMT
Accept-Ranges: bytes
Date: Sat, 15 Oct 2016 13:16:47 GMT
X-Varnish: 1925846734
Age: 0
Via: 1.1 varnish
Connection: keep-alive
X-Cache: MISS

Disabled :

HTTP/1.1 200 OK
Server: nginx
Content-Type: text/html; charset=UTF-8
X-Powered-By: PHP/5.6.26
Last-Modified: Sat, 15 Oct 2016 13:00:08 GMT
Vary: Accept-Encoding
Date: Sat, 15 Oct 2016 13:17:06 GMT
X-Varnish: 1925848050 1925847866
Age: 2
Via: 1.1 varnish
Connection: keep-alive
X-Cache: HIT

In a big concurrent visitor enviroment the Expire header in the past, mean all request (basically GET) cannot cached, and the page need to be reload, with a lot of PHP and MySQL Load, until server crash.

Please remove this “feature” … it’s useless and a serious bug.

Best Regards,

Marco Marcoaldi