No converter available for format gcmd_dif 

 (Exception: Traceback (most recent call last):
  File "/usr/lib/ckan/default/src/ckanext-package_converter/ckanext/package_converter/logic.py", line 113, in export_as_record
    raise #Exception('Cannot convert')
TypeError: exceptions must be old-style classes or derived from BaseException, not NoneType
)