Symptoms

There is a workflow step in a process that should generate a PDF from a SmartForm and then email it to the destination user. However, when the email arrives with the attached PDF, it seems there is a K2 error message displayed in the PDF, but unfortunately it's been cut off at the top and we can only see the "OK" and "Details" buttons.
 

Diagnoses

We did some diagnostics, for example we enabled full K2 Host Server logging and full SmartObject logging but couldn't determine any error message. We also enabled K2 PDF Service logging as per this article: http://help.k2.com/kb001626.aspx and saw what looked to be a 401 error, so we assumed it was a credential issue. We changed the Authentication Method on the PDF Service Instance to use the K2 Service Account, but that didn't resolve the issue.
 

Resolution

At the end of the day it came down to how the step in the workflow was created. The URL that was supposed to open the form using the serial number and other input parameters was built incorrectly. After changing the URL to include an underscore and changing the rules in the Form to reflect the building of the Form correctly, it is working now and the authentication method can be set back to using Impersonation.