Plone 6 migration errors.

[arky]

Plone 6 migration ( from:6002 To: 6004) fail with following attribute error.

Upgrade aborted. Error:
Traceback (most recent call last):
  File "/app/lib/python3.9/site-packages/Products/CMFPlone/MigrationTool.py", line 297, in upgrade
    step['step'].doStep(setup)
  File "/app/lib/python3.9/site-packages/Products/GenericSetup/upgrade.py", line 185, in doStep
    self.handler(tool)
  File "/app/lib/python3.9/site-packages/plone/app/upgrade/v60/alphas.py", line 146, in fix_unicode_properties
    portal.ZopeFindAndApply(portal, search_sub=1, apply_func=fix_properties)
  File "/app/lib/python3.9/site-packages/OFS/FindSupport.py", line 171, in ZopeFindAndApply
    self.ZopeFindAndApply(ob, obj_ids, obj_metatypes,
  File "/app/lib/python3.9/site-packages/OFS/FindSupport.py", line 171, in ZopeFindAndApply
    self.ZopeFindAndApply(ob, obj_ids, obj_metatypes,
  File "/app/lib/python3.9/site-packages/OFS/FindSupport.py", line 116, in ZopeFindAndApply
    for id, ob in items:
  File "/app/lib/python3.9/site-packages/ZTUtils/Lazy.py", line 197, in __getitem__
    value = data[index] = self._func(self._seq[index])
  File "/app/lib/python3.9/site-packages/plone/folder/ordered.py", line 102, in <lambda>
    return LazyMap(lambda id, _getOb=self._getOb: (id, _getOb(id)),
  File "/app/lib/python3.9/site-packages/plone/folder/ordered.py", line 65, in _getOb
    return super(OrderedBTreeFolderBase, self)._getOb(id, default)
  File "/app/lib/python3.9/site-packages/Products/BTreeFolder2/BTreeFolder2.py", line 219, in _getOb
    return self._tree[id].__of__(self)
AttributeError: 'InfrastructureProject' object has no attribute '__of__'
End of upgrade path, main migration has finished.
The upgrade path did NOT reach current version.
Migration has failed