Comment 2 for bug 533992

Thanks for your report

The relevant error is:
---
Configurando postfix (2.6.5-3) ...

Postfix configuration was not changed. If you need to make changes, edit
/etc/postfix/main.cf (and others) as needed. To view Postfix configuration
values, see postconf(1).

After modifying main.cf, be sure to run '/etc/init.d/postfix reload'.

Running newaliases
newaliases: warning: valid_hostname: numeric hostname: 10
newaliases: fatal: file /etc/postfix/main.cf: parameter mydomain: bad parameter value: 10
dpkg: error al procesar postfix (--configure):
 el subproceso script post-installation instalado devolvió el código de salida de error 75

This error is caused by a bad postfix configuration. Please correct it and try performing the upgrade again.

Thanks.