Critical error on trying to serialize entry

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/mongodb_mirror/mirror.py", line 101, in sync_client
    data = self._serialize_document(data, collection)
  File "/procedure_mirror/procedure_mirror/main.py", line 17, in _serialize_document
    return load_procedure(migrated_data).to_primitive(app_data={'locale': '__all__'}, role='public')
  File "/usr/local/lib/python3.8/site-packages/prozorro_sale/procedure/model_generator.py", line 62, in load_procedure
    return get_procedure_type_from_data(data).trusted_load(data)
  File "/usr/local/lib/python3.8/site-packages/schematics/models.py", line 136, in trusted_load
    raise ConversionError(f"Failed to load '{key}' field, cause of {e}")
schematics.exceptions.ConversionError: ["Failed to load 'awards' field, cause of {\"daf0ce1a97d146c8bfc18230838c948a\": [\"Failed to load 'items' field, cause of {\\\"54f50546e330444f93cb9e2e78e5ff14\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"], \\\"73dd392f51a246c9b7392c7e3b4bfb83\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"]}\"], \"26d9fbcc6a734dc19537d11730bb3d57\": [\"Failed to load 'items' field, cause of {\\\"54f50546e330444f93cb9e2e78e5ff14\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"], \\\"73dd392f51a246c9b7392c7e3b4bfb83\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"]}\"]}"]
[2021-03-26T08:43:14.292Z] | mongodb_mirror.mirror | ERROR - Critical error on trying to serialize entry - ["Failed to load 'awards' field, cause of {\"daf0ce1a97d146c8bfc18230838c948a\": [\"Failed to load 'items' field, cause of {\\\"54f50546e330444f93cb9e2e78e5ff14\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"], \\\"73dd392f51a246c9b7392c7e3b4bfb83\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"]}\"], \"26d9fbcc6a734dc19537d11730bb3d57\": [\"Failed to load 'items' field, cause of {\\\"54f50546e330444f93cb9e2e78e5ff14\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"], \\\"73dd392f51a246c9b7392c7e3b4bfb83\\\": [\\\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\\\"]}\"]}"] | X-Request-ID: b0b14aac-5cf8-4878-bf57-f90d4703957a
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/schematics/models.py", line 134, in trusted_load
    obj.__data[key] = obj.fields[key](val, context)
  File "/usr/local/lib/python3.8/site-packages/schematics/types/base.py", line 226, in __call__
    return self.convert(value, context)
  File "/usr/local/lib/python3.8/site-packages/schematics/types/compound.py", line 51, in convert
    return self._convert(value, context)
  File "/usr/local/lib/python3.8/site-packages/prozorro_sale/procedure/models/types.py", line 128, in _convert
    raise exceptions.CompoundError(errors)
schematics.exceptions.CompoundError: {"daf0ce1a97d146c8bfc18230838c948a": ["Failed to load 'items' field, cause of {\"54f50546e330444f93cb9e2e78e5ff14\": [\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\"], \"73dd392f51a246c9b7392c7e3b4bfb83\": [\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\"]}"], "26d9fbcc6a734dc19537d11730bb3d57": ["Failed to load 'items' field, cause of {\"54f50546e330444f93cb9e2e78e5ff14\": [\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\"], \"73dd392f51a246c9b7392c7e3b4bfb83\": [\"Failed to load 'additionalClassification' field, cause of 'additionalClassification'\"]}"]}

During handling of the above exception, another exception occurred: