Export of some old and complex projects is not working

tvbadmin@debian64:~/TVB_Distribution/bin$ sh distribution.sh start COMMAND_PROFILE -headless
Executing distribution.sh
>>> from tvb.interfaces.command.demos.project.project_export import run_export
>>> run_export(31)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/interfaces/command/demos/project/project_export.py", line 55, in run_export
    export_file = mng.export_project(project, loose_irrelevant)
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/adapters/exporters/export_manager.py", line 276, in export_project
    self._export_bursts(project, project_datatypes, zip_file)
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/adapters/exporters/export_manager.py", line 219, in _export_bursts
    self._build_burst_export_dict(burst, bursts_dict)
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/adapters/exporters/export_manager.py", line 352, in _build_burst_export_dict
    wf_steps, view_steps = self._build_workflow_step_info(workflow)
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/adapters/exporters/export_manager.py", line 325, in _build_workflow_step_info
    wf_step_info.set_algorithm(linked_algorithm)
  File "/home/tvbadmin/TVB_Distribution/tvb_data/lib/python2.7/site-packages/tvb/core/entities/transient/burst_export_entities.py", line 234, in set_algorithm
    self._data_dict[self.ALGO_INFO] = {'module': algorithm.algo_group.module,
AttributeError: 'NoneType' object has no attribute 'algo_group'