Fix for open_basedir not in allowed path(s) message

When you are trying to auto update plugins via the build-in updater you might get error messages like:

Warning: file_exists() [function.file-exists]: open_basedir restriction
in effect. File(/var/tmp//1220989448) is not within the allowed
path(s): (/home/usr123/:/tmp:/usr/local/lib/php/) in /usr/home/usr123
/../wp-includes/functions.php on line 1960

Warning: touch() [function.touch]: open_basedir restriction in effect.
File(/var/tmp/1220989448) is not within the allowed path(s): (/home
/usr123/:/tmp:/usr/local/lib/php/) in /usr/home/usr123/../wp-admin
/includes/file.php on line 122

Warning: fileowner() [function.fileowner]: open_basedir restriction
in effect. File(/var/tmp/1220989448) is not within the allowed
path(s): (/home/usr123/:/tmp:/usr/local/lib/php/) in /usr/home/usr123
/../wp-admin/includes/file.php on line 487

Warning: unlink() [function.unlink]: open_basedir restriction in effect.
File(/var/tmp/1220989448) is not within the allowed path(s): (/home
/usr123/:/tmp:/usr/local/lib/php/) in /usr/home/usr123/../wp-admin
/includes/file.php on line 489

Today, I got it fix by adding a single line to the wp-config.php file ??

Just have a look at the following section: allowed path(s): (/home/usr123/:/tmp:/usr/local/lib/php/)

In it, there is /tmp which is obviously way different then the via the get_temp_dir function (/wp-admin/includes/file.php:97) collected /var/tmp !!

So in order to fix this just add the following string to the wp-config.php:

define('WP_TEMP_DIR','/tmp');

The solution couldn’t be easier found than by looking at the get_temp_dir function itself and a quick search through the whole WP source code ??

function get_temp_dir() {
  if ( defined('WP_TEMP_DIR') )
    return trailingslashit(WP_TEMP_DIR);