Laravel mail with attachment gives fopen(): null bytes error

I am trying to send an email with a pdf file attached to it. I checked and the file does exist at the path. I can open it aswell. I tested if i can download the file with the download function of the storage facade and that also worked.

However when i try it in a queued email, it fails everytime after waiting about 20 seconds. This is the error i got:

ValueError: fopen(): Argument #1 ($filename) must not contain any null bytes in C:\Users\Gebruiker\PhpstormProjects\FuegoWebsite\vendor\swiftmailer\swiftmailer\lib\classes\Swift\ByteStream\FileByteStream.php:129
Stack trace:

And my email code is:

<?php

namespace App\Mail;

use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Storage;

class PdfTestMail extends Mailable
{
    use Queueable, SerializesModels;

    public $orderId;
    public $text;

    /**
     * Create a new message instance.
     *
     * @return void
     */
    public function __construct($orderid, $text)
    {
        $this->orderId = $orderid;
        $this->text = $text;
    }

    /**
     * Build the message.
     *
     * @return $this
     */
    public function build()
    {
        $file = Storage::disk('private')->get("factuur_order_".$this->orderId.'.pdf');
        return $this->text('emails.notifyAdmin')
            ->subject('Orderbevestiging #'.$this->orderId)
            ->attach($file, [
                'as' => 'factuur.pdf',
                'mime' => 'application/pdf'
            ]);
    }

}

I tried to attach the pdf in multiple ways, including the direct output of the barryvdh/dompdf package i use to generate a pdf. nothing works and i have no idea why.

The attach method takes a filename for the file to attach, not data. You are probably looking for the attachData method:

public function attachData($data, $name, array $options = [])

To switch to attachData:

->attachData($file, 'factuur.pdf', ['mime' => 'application/pdf'])

Laravel 8.x Docs - Mail - Attachments - Raw Data Attachments attachData