Why do I receive the error 'Subject cannot be blank' when attempting to save or deploy message templates?
This particular error is cause by a null value in the database record for the message template. You will need to verify the subject field is populated for the message template throwing the error or where no subject exists (i.e. as can be the case for the Print templates).
In order to resolve this issue, submit a service request via Ask Technical Support that specifies the template or templates that are encountering the issue and when the behavior began occurring.