To increase the file upload size we have to edit two values in php.ini:
upload_max_filesize and post_max_size
; Whether to allow HTTP file uploads.
file_uploads = On
; Maximum allowed size for uploaded files.
upload_max_filesize = 20M
; Maximum size of POST data that PHP will accept.
post_max_size = 20M
; Maximum number of files that can be uploaded via a single request
max_file_uploads = 25
After editing the php.ini don't forget to restart apache service.