Symptoms
When converting a form to PDF and adding it as an attachment to an email, the email is not sent.
Diagnoses
The HostServer log shows the error "An error occurred in the PDFConverterService service instance. Failed to convert URL to PDF" indicating that the attachment was not added successfully, preventing the email from sending.
Resolution
Ensure that "Automatic logon with current user name and password" in Internet Options > Trusted Sites > Custom Level > User Authentication is enabled, and then restart the K2 service.