La web da error
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, webmaster@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
En el error.log de apache aparece el siguiente mensaje.
Invalid command 'RewriteEngine', perhaps mis-spelled or defined by a module not included in the server configuration
Solucion
Debemos activar el modulo rewrite
sudo a2enmod rewrite
