I have written below code in Mail/Mails.php file build function.
return $this->from(config('app.FROM_EMAIL'),config('app.MAIL_FROM_NAME'))
->subject($this->subject)
->view('emails.generalmail')
->attachData($this->attach,'file_pdf.pdf');
Error
Unable to JSON encode payload. Error code: 5
I used Dompdf email send with attachment.
I'm not sure what version of Laravel you are on so it could be slightly different but you need to use the attach
function rather than attachData
return $this->from(config('app.FROM_EMAIL'),config('app.MAIL_FROM_NAME'))
->subject($this->subject)
->view('emails.generalmail')
->attach('[PATH TO FILE]');
See more here: Laravel Mail Docs
Change the version at the top.