I have installed ISPConfig 3 on an Ubuntu VPS and configured it for Apache + PHP via FastCGI and suexec. I am able to upload PHP apps (e.g. Wordpress) and run them normally w/ suexec.

However, for some reason the PHP scripts cannot write data to disk. For instance, trying to upgrade a plugin via Wordpress' web interface causes it to fail with the error "Could not create directory /path/to/wp-content/upgrade/plugin.tmp."

Trying to upload media and other assets also fails via the web.

I've checked owner/group on the directory structure and it looks good. The suExec log also seems to be normal and I don't see any indicative errors in the web server logs.

I can also confirm that changing the owner/group on the directories does result in the expected error in suexec.log.

Additionally, I have the directory permissions set to u=rw,g=r,o= and I've also tried setting g=rw.

None of this results in my scripts being able to write to the directories. What am I doing wrong?