diff --git a/lib/galaxy/model/__init__.py b/lib/galaxy/model/__init__.py
index 3df40b27bc0e..c8128a19b730 100644
--- a/lib/galaxy/model/__init__.py
+++ b/lib/galaxy/model/__init__.py
@@ -1838,7 +1838,8 @@ def io_dicts(self, exclude_implicit_outputs=False) -> IoDicts:
                 if obj.name not in out_data:
                     out_collections[obj.name] = obj.dataset_collection_instance
                 # else this is a mapped over output
-        out_collections.update([(obj.name, obj.dataset_collection) for obj in self.output_dataset_collections])
+        if not exclude_implicit_outputs:
+            out_collections.update([(obj.name, obj.dataset_collection) for obj in self.output_dataset_collections])
         return IoDicts(inp_data, out_data, out_collections)
 
     # TODO: Add accessors for members defined in SQL Alchemy for the Job table and
diff --git a/test/unit/data/model/test_model.py b/test/unit/data/model/test_model.py
index 692578533dc5..4ec6c459af8a 100644
--- a/test/unit/data/model/test_model.py
+++ b/test/unit/data/model/test_model.py
@@ -18,3 +18,27 @@ def test_get_uuid():
 def test_permitted_actions():
     actions = model.Dataset.permitted_actions
     assert actions and len(actions.values()) == 2
+
+
+def test_io_dicts_excludes_implicit_output_collections():
+    """Regression test for https://github.com/galaxyproject/galaxy/issues/22015
+
+    When a tool with an explicit collection output is mapped over a list,
+    each job gets a JobToImplicitOutputDatasetCollectionAssociation pointing
+    to a DatasetCollection with precreated (unpopulated) elements.
+    io_dicts(exclude_implicit_outputs=True) must exclude these to avoid
+    crashes during metadata serialization on unpopulated elements.
+    """
+    job = model.Job()
+    dc = model.DatasetCollection(collection_type="paired")
+    assoc = model.JobToImplicitOutputDatasetCollectionAssociation(name="paired_output", dataset_collection=dc)
+    job.output_dataset_collections.append(assoc)
+
+    # With exclude_implicit_outputs=True, output_dataset_collections must be excluded
+    io = job.io_dicts(exclude_implicit_outputs=True)
+    assert "paired_output" not in io.out_collections
+
+    # With exclude_implicit_outputs=False (default), they should be included
+    io = job.io_dicts(exclude_implicit_outputs=False)
+    assert "paired_output" in io.out_collections
+    assert io.out_collections["paired_output"] is dc