WordPress write to disk issues (LAMP, Ubuntu 14.04)
Everything was working fine until suddenly WordPress can't write anything to disk, such as update plugins, upload media, etc. Also as a result of this, w3 total cache doesn't work, because it can't write to disk.
I have checked to make sure that permissions are set to 755 and owner is www-data (apache user).
Temporarily swithching permissions to 775 or 777 and running an update still didn't work.
I have even tried to recreate the uploads and upgrade directories.
Nothing works. Any suggestions on a fix for this?