Hey user92271,
Our engineers are aware of the server error and are investigating this with priority. Please contact us via private message on FaceBook or Twitter (@ QuickBooksUK) with the email address associated with your account so that we can add you to the investigation and send automatic notification when the issue is resolved, as the address will be redacted for security if you enter on the community. We apologise for the inconvenience caused, in the meantime as a workaround you can send the invoice manually by selecting 'Print/Preview', download the PDF and send via your own email.
Thanks
