Using 2015-08-10a "Detritus" I'm having the following problem. I did have the same problem with earlier versions as well.
My distro is Gentoo.
I have a working system with PHP 5.5.29 .
If I change nothing but the PHP version to 5.6.13 I get this on my Farm:
Warning: session_start(): open(/tmp/sess_rmi1sagflrnmrm9928j9l80no2, O_RDWR) failed: Permission denied (13) in /home/web/doku/farmer/inc/init.php on line 154
DokuWiki Setup Error
The datadir ('pages') at /home/web/doku/farm/www.kpaddock.com/conf/../data/pages is not found, isn't accessible or writable. You should check your config and permission settings. Or maybe you want to run the installer?
Warning: Unknown: open(/tmp/sess_rmi1sagflrnmrm9928j9l80no2, O_RDWR) failed: Permission denied (13) in Unknown on line 0
Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0
What do I need to fix?