There are two main causes for this issue:
The most likely cause is due to a mishandling of email attachments when multiple film profiles are attached to one email. The current solution is to send each film profile in a separate email. We're currently investigating the cause of this issue which has affected a very small percentage of users. We currently believe it to be a problem with some email clients that are creating invalid email attachments. If you are experiencing this issue when attaching multiple film profiles, please open up a support request so that we can gather more data on the issue.
The other less likely cause of this error message is that you are using a film profile that was exported using an older version of Plotter for Windows. You will need to re-export your film data using the latest version of Plotter for Windows to resolve this issue. The latest version of Plotter is 18.104.22.168 as seen in the Help | About menu option.
Please contact http://ViewCameraStore.com for updating to the latest version of Plotter for Windows or to get your updated film profile files.