Laravel - mimes：pdf无效

I have a form with an input which allows to upload PDFs.

Here is the method that validates my input :

protected function validator(array $data)
{
    return Validator::make($data, [
        'title' => 'required|max:255|string',
        'artist' => 'required',
        'notes' => 'nullable|string',
        'file' => 'required|mimes:pdf|max:500',
        'g-recaptcha-response' => 'required|captcha',
    ]);
}

The rules are working for all the other fields, but it does not work for the file input. Whatever I upload, PDF or not, I have the following error :

The file must be a file of type: pdf.

I just solved my issue.

In case someone has the same problem, you need to set the enctype attribute of your form to multipart/form-data.

In short, something like this :

<form action="#" enctype="multipart/form-data">
    ...
</form>

The error is not very clear, so I hope this helps.