This is driving me absolutely nuts!
I have taken a backup of my online site and am working on a local copy prior to upgrade. Apache is running as www-data and i can see that configuration.php is writable by that user as are all the directories. However, 'Directory Permissions' in admin tells me otherwise.
There are old (server) paths in the config visible through admin. These are unchangeable. It's as if the installation is looking at a completely different config file to the one i'm editing and it has the old server paths in it, but HOW could that be?