Empty session files on vagrant box

Question

I have a vagrant box with a Magento installation. My var folder is set to 777 (not recommended I know but I'm trying everything). When I try to login to the admin, nothing happens. I see empty session files in the var/session folder.

I have checked the following:

• cookie domain in db (set to empty)
• vagrant box server time equals my local time zone
• use of localhost (I'm not using localhost, i'm using a local.XXXX.com domain)
• cleared all my cookies
• tried various browsers
• tried incognito browser

I keep seeing this in the logs:

Warning: Unknown: Failed to write session data (files). Please verify
that the current setting of session.save_path is correct [path to
correct var/session folder]

but there are empty session files in that folder.

I tried deleting the session folder, and Magento creates it anew but with the empty session files.

I had the same configuration running perfectly, but I had to destroy and rebuild the vagrant box. That is when it started happening.

Answer 1

Turns out it had something to do with the version of PHP I was running (5.4.34). I downgraded to version PHP 5.3.3 (which matches our production box) and everything worked.

UPDATE

It just started happening again. I updated local.xml as follows:

<config>
    <global>
        ...
        <session_save><![CDATA[files]]></session_save>
        <session_save_path>
            <![CDATA[/tmp/session]]>
        </session_save_path>
     </global>
     ...
</config>

Discovered here: https://stackoverflow.com/questions/26123081/failed-to-write-session-data-magento