Laravel file does not exist - file upload

Probably the problem is the "upload_max_filesize" that has been exceeded (check your php.ini), however it is a good practice to first check if the file is valid.

if (!$file->isValid()) {
    throw new \Exception('Error on upload file: '.$file->getErrorMessage());
}
//...

In the php.ini file, change the following:

upload_max_filesize = 20M
post_max_size = 20M

This should make it work.