AttributeError: 'NoneType' object has no attribute 'serialize'

[galaxyproject-sentryintegration]

Sentry Issue: GALAXY-MAIN-4KSCZZZ0014D2

AttributeError: 'NoneType' object has no attribute 'serialize'
(11 additional frame(s) were not displayed)
...
  File "galaxy/model/__init__.py", line 7798, in _serialize
    collection=self.collection.serialize(id_encoder, serialization_options),
  File "galaxy/model/__init__.py", line 513, in serialize
    return self._serialize(id_encoder, serialization_options)
  File "galaxy/model/__init__.py", line 7484, in _serialize
    elements=[e.serialize(id_encoder, serialization_options) for e in self.elements],
  File "galaxy/model/__init__.py", line 513, in serialize
    return self._serialize(id_encoder, serialization_options)
  File "galaxy/model/__init__.py", line 8224, in _serialize
    rval["child_collection"] = element_obj.serialize(id_encoder, serialization_options)

(75207747) Failure preparing job

[dannon]

Triage Summary

During job preparation, a DatasetCollectionElement's element_object property returns None (all of hda, ldda, and child_collection are None), and _serialize() at lib/galaxy/model/__init__.py:8224 calls .serialize() on it without a null check. This indicates an orphaned collection element — a data integrity issue where a collection element's referenced dataset/collection has been deleted or never properly linked.

Severity: High — causes job preparation failure, blocking execution. Blast radius: Users with corrupted collection elements (rare but blocks workflows). Complexity: Low — add null guard on element_obj in _serialize(). Recommendation: Next release, consider also investigating how orphaned elements are created.

Full triage: https://gist.github.com/dannon/5bc446c6c418d7df2e861eb004fa48f7