I get similar errors in my error_log in php when users are uploading their files
PHP Warning: POST Content-Length of 11933650 bytes exceeds the limit of 8388608 bytes in Unknown on line 0
upload_max_filesize = 1000M ;1GB
post_max_size = 1000M
8388608 bytes is 8M, the default limit in PHP. Those changes to php.ini should indeed solve the problem (make sure your restart your Apache server after making them).
Memory limit shouldn't need to be changed here.