If you created a multipart/form-data form to upload a file to your server and it gives you an error 1 (UPLOAD_ERR_INI_SIZE) , you need to update the php.ini for your machine.
PHP.ini is usually found in /etc/ directory of your server. On my AWS AIM Linux instance the current PHP Version is 5.6 and thus the file to edit is /etc/php-5.6.ini
Edit the ini file to find the upload_max_filesize variable and update it to something more appropriate for your needs. The default on my instance was 2M and that caused me headaches no end.
To reload the php.ini you can ask the server to gracefully restart apache with sudo apachectl -k graceful
PHP File Upload with UPLOAD_ERR_INI_SIZE