Could not load installer script from tools/extender.pl.

If this is a TWiki release prior to 4.2, please download the
latest version of the script from:

http://twiki.org/cgi-bin/view/Codev/ExtenderScript

and place it in the 'tools' directory below your installation
root (create the directory if necessary).

If this is TWiki 4.2 or later, the script is missing from
your installation, or may be broken.