Fatal Error: Fontfile not found or not readable

If you see this error when accessing User Registration, My Account, or a CiviCRM Profile in create or edit mode, then you need to either "turn off" the CAPTCHA setting for the profile...Administer CiviCRM >> CiviCRM Profiles >> Settings

Uncheck ... Include CAPTCHA?

or...

Review and correct the CAPTCHA settings in civicrm.settings.php using the inline documentation in that file:

   define( 'CIVICRM_CAPTCHA_FONT_PATH', '' );
   define( 'CIVICRM_CAPTCHA_FONT'     , '' );

Note that the referenced font file MUST be a true-type font (generally filename extension will be .ttf).