Wiki error

I'm trying use wiki [1.0.4] and I receive this error , when I try acess revisions [compare] and save the slug
[same msg error]

Warning: Cannot modify header information - headers already sent by (output started at /var/www/infra/wp-content/themes/platformpro/header.php:14) in /var/www/infra/wp-includes/pluggable.php on line 897

How I can fix this?
Thank you in advance

@edit : I use full version