Error Communicating with FrameMaker
This is most likely caused by the ePublisher plugin for FrameMaker not being correctly installed for the version of FrameMaker that ePublisher is trying to use to generate your output.
Steps to fix (applies to version 2017.1 and above, contact Support for older versions of ePublisher):
Make sure all FrameMaker instances are shutdown and no background instances are running.
Make sure both FrameMaker and ePublisher are both the same "bitness", meaning they both are 32-bit or both are 64-bit applications.
If you have more than one FrameMaker, make sure the one ePublisher uses is the one that "opens" by default from Windows Explorer.
Run the ePublisher Express installer's 'Update/Repair' option to fix the FrameMaker connection.
In addition, there was an update to Adobe FrameMaker 2020 (version 2) that requires a patch located at:
https://webworks.com/Support/ePublisher/2020/2020_1/
Download: EPUB2343_FM2020_Apiclient.zip.