I am using a solution of vbox (virtual box) and shared folders in our windows work environment (yes, unfortunatelly, but the IT team is in his right to decide which machines we have to use).

Everytime the vbox start, it mounts "automagically" one of the shared folders in the linux host (centos and archlinux, one day I will explain why). So then, apache has all what he needs in /var/www/html/ (simply mounted with "mount /var/www/html") (see automatically mount directories in vbox).

So far, everything was working fine... until I started to make small changes in small files. Absolutely surprising because when I deleted the complete code in the css or js file, for example, and I updated the browser, the screen appeared white, so everything seemed ok. But not at all, dealing with small changes, like adding a line in your css simply add no effect, the change is here, but seems that Apache or the browser didn't like it, simply it was being ignored.

After a while struggling about the browsers cache and even restarting the virtual box I finally decided to dig into Google.

I found the problem in the frankooh blog and it seems that it is a vbox problem, exactly a vboxsf problem with Apache.

The solution is simple, go to you apache configuration (in centos /etc/http/conf/httpd.conf) and uncomment the line:

EnableSendfile Off

After restarting Apache all the changes were sended to the browser without problems, even the small ones.

PS: be carefull with case sensitive off != Off