I think that if u got a small /tmp like i had u cant upload big file…
My /tmp = 462M so i can upload only file less or egal 500M.

I input upload_tmp_dir = /var/www/nextcloud/data/upload-tmp in php.ini to use it
modify :
upload_max_filesize = xxxG
post_max_size = xxxG
output_buffering = 0
max_input_time 7200
max_execution_time 7200
memory_limit = 1024M

comment in .htaccess :
php_value upload_max_filesize xxxx
php_value post_max_size xxxx
php_value memory_limit xxxx

Now i can upload BIG FILE depend on upload_max_filesize and post_max_size.
I upload 9G with upload_max_filesize and post_max_size = 10G.
Everything with working good now.