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phpMyAdmin "Cannot start session without errors"

Posted October 22nd, 2008 in PHP

Yesterday one of my customers reported their phpMyAdmin install was showing the error message "Cannot start session without errors" and they were unable to even get to the phpMyAdmin login page. This post looks at what caused the issue and how to fix it.

The error message in question looks like this:

phpMyAdmin - Error

Cannot start session without errors, please check errors given in your PHP and/or webserver log file and configure your PHP installation properly.

Clearly there's something wrong with the way sessions are being used. I checked the Apache error log file and it didn't actually show any error messages and I don't have PHP logging errors separately.

The next step was to have a look at the php.ini file and see what the session settings are. This is on a CentOS 5 webserver with a default install. I've removed all the unecessary comments etc:

[Session]
session.save_handler = files
session.save_path = "/var/lib/php/session"
session.use_cookies = 1
session.name = PHPSESSID
session.auto_start = 0
session.cookie_lifetime = 0
session.cookie_path = /
session.cookie_domain =
session.serialize_handler = php
session.gc_probability = 1
session.gc_divisor     = 1000
session.gc_maxlifetime = 1440
session.bug_compat_42 = 0
session.bug_compat_warn = 1
session.referer_check =
session.entropy_length = 0
session.entropy_file =
session.cache_limiter = nocache
session.cache_expire = 180
session.use_trans_sid = 0
session.hash_function = 0
session.hash_bits_per_character = 5

I couldn't see anything wrong there, so I figured the next logical step was to check the directory specified by the session.save_path option as follows:

ls -l /var/lib/php
total 2
drwxrwx--- 2 root apache 2048 Jul 17 11:56 session

That shows us that the session directory is owned by "root", the user is "apache" and it can be written to by both user and group but no one else. That all looks fine but we run this particular webserver as a user other than "apache".

It would therefore appear that when I did an upgrade of PHP a little while back it restored the user permissions back to root:apache instead of leaving them root:myusername (myusername isn't the actual username in question - just an example). I am making an assumption here because there shouldn't be any other reason for the permissions to have changed.

A simple chown is all that's required:

sudo chown -R root:myusername /var/lib/php/session

and then the error in phpMyAdmin went away and we were able to log in again.

So, assuming I am correct that a PHP upgrade on CentOS restored the PHP session directory default permissions, if you run Apache on CentOS as a user other than "apache" you need to make sure you check the permissions of your PHP session directory after upgrading. This will affect any websites using PHP file based sessions, not just phpMyAdmin.