UnicodeDecodeError in mailer attach

[josejachuf]

Hi @gi0baro

Frequently use mailer, but I hadn't used it with Attach.

I want, after the submit of the form, send an email with the file attached from the form

if form.accepted:        
    msg = mailer.mail(subject="My Subject")
    msg.recipients = ['[email protected]']
    msg.html = '<p>My HTML Message</p>'
    _path = os.path.join(app.root_path, 'uploads', row.my_upload_field)        
    with open(_path) as fp:
        msg.attach(filename=_path, data=fp.read())
    msg.send()

But an error occurs:

msg.attach(filename=_path, data=fp.read())
File "/usr/local/lib/python3.9/codecs.py", line 322, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte

The UnicodeDecodeError error is known, especially when I used strings at Python2.7, but I don't understand why reading the file.

With this it also gives the error:

with open(_path, encoding='utf-8') as fp:
    msg.attach(filename=_path, data=fp.read())

The attached file is in this case a JPG, but it could be another type of image or also a PDF

[josejachuf]

This works fine:

with open(_path, 'rb') as fp:
    msg.attach(filename=_path, data=fp.read())