I've done "chmod -R 777" data and "chmod -R 777 internal_data"
I also put the chown correctly, in my case, apache: apache
The error log show this:
ErrorException: copy(/var/www/html/myforum/internal_data/attachments/3/3563-8b386c147966fccd5840d5e70694587b.data): failed to open stream: Permission denied -library/XenForo/Helper/File.php:253
I think the problem is in the permissions but, in what permissions?. What should I do more? .