Outdated: Pathauto causing Fatal error: Call to undefined function: ctype_alnum()

On certain systems the ctype functions are not installed and therefore the use of Pathauto can result in the following error:

The line number may be different depending on your version of pathauto but the basic error is the same.

The solution to this problem depends on your platform, but the basic resolution is to install the ctype functions.

FreeBSD Solution:

As root (or sudo) from the command line you need to install the php5-ctype port.

SuSE

The package is also named php5-ctype, and can be installed using YAST.

Other Platforms

Advice for other platforms is welcomed to be added in comments, though most platforms have this installed by default.

You can see this issue from the Pathauto queue for more information and othe rpossible solutions.