[Thu May 04 13:01:48.378031 2017] [core:alert] [pid 13353:tid 547981033904] [client 192.168.0.120:44978] /var/www/owncloud/htdocs/.htaccess: Invalid command 'php_value', perhaps misspelled or defined by a module not included in the server configuration
The problem is that the .htaccess file shipped with owncloud 10 do not protect the php_value directives and probably a lot of server relay on php-fpm instead of the php module.
Editing the .htaccess this way:
php_value upload_max_filesize 513M
php_value post_max_size 513M
php_value memory_limit 512M
php_value mbstring.func_overload 0
php_value default_charset 'UTF-8'
php_value output_buffering 0
fixes the 500 error but owncloud keeps complaining that .htaccess has been modified.......