diff --git a/client/src/api/schema/schema.ts b/client/src/api/schema/schema.ts
index b8a076a8e0ac..373d5d14556b 100644
--- a/client/src/api/schema/schema.ts
+++ b/client/src/api/schema/schema.ts
@@ -12568,7 +12568,12 @@ export interface components {
              * Value
              * @description The values of the job parameter
              */
-            value?: components["schemas"]["EncodedJobParameterHistoryItem"][] | number | boolean | string | null;
+            value?:
+                | (components["schemas"]["EncodedJobParameterHistoryItem"] | null)[]
+                | number
+                | boolean
+                | string
+                | null;
         };
         /**
          * JobSourceType
diff --git a/client/src/components/Collections/common/CollectionEditView.vue b/client/src/components/Collections/common/CollectionEditView.vue
index 5b711d143af6..30992cf83df1 100644
--- a/client/src/components/Collections/common/CollectionEditView.vue
+++ b/client/src/components/Collections/common/CollectionEditView.vue
@@ -53,9 +53,26 @@ const collectionChangeKey = ref(0);
 const attributesData = computed(() => {
     return collectionAttributesStore.getAttributes(props.collectionId);
 });
+const attributesLoadError = computed(() =>
+    errorMessageAsString(collectionAttributesStore.hasItemLoadError(props.collectionId))
+);
+
 const collection = computed(() => {
     return collectionStore.getCollectionById(props.collectionId);
 });
+const collectionLoadError = computed(() => {
+    if (collection.value) {
+        return errorMessageAsString(collectionStore.hasLoadingCollectionElementsError(collection.value));
+    }
+    return "";
+});
+watch([attributesLoadError, collectionLoadError], () => {
+    if (attributesLoadError.value) {
+        errorMessage.value = attributesLoadError.value;
+    } else if (collectionLoadError.value) {
+        errorMessage.value = collectionLoadError.value;
+    }
+});
 const databaseKeyFromElements = computed(() => {
     return attributesData.value?.dbkey;
 });
@@ -101,7 +118,7 @@ async function clickedSave(attribute: string, newValue: any) {
         body: { dbkey: dbKey },
     });
     if (error) {
-        errorMessage.value = errorMessageAsString(error, "History import failed.");
+        errorMessage.value = errorMessageAsString(error, `Changing ${attribute} failed.`);
     }
 }
 
@@ -119,7 +136,7 @@ async function clickedConvert(selectedConverter: any) {
         await axios.post(url, data).catch(handleError);
         successMessage.value = "Conversion started successfully.";
     } catch (err) {
-        errorMessage.value = errorMessageAsString(err, "History import failed.");
+        errorMessage.value = errorMessageAsString(err, "Conversion failed.");
     }
 }
 
@@ -148,14 +165,14 @@ async function clickedDatatypeChange(selectedDatatype: any) {
     });
 
     if (error) {
-        errorMessage.value = errorMessageAsString(error, "History import failed.");
+        errorMessage.value = errorMessageAsString(error, "Datatype change failed.");
         return;
     }
     successMessage.value = "Datatype changed successfully.";
 }
 
 function handleError(err: any) {
-    errorMessage.value = errorMessageAsString(err, "History import failed.");
+    errorMessage.value = errorMessageAsString(err, "Datatype conversion failed.");
 
     if (err?.data?.stderr) {
         jobError.value = err.data;
@@ -198,14 +215,14 @@ async function saveAttrs() {
             {{ localize(infoMessage) }}
         </BAlert>
 
-        <BAlert v-if="jobError" show variant="danger" dismissible>
+        <BAlert v-if="errorMessage" show variant="danger">
             {{ localize(errorMessage) }}
         </BAlert>
 
         <BAlert v-if="successMessage" show variant="success" dismissible>
             {{ localize(successMessage) }}
         </BAlert>
-        <BTabs class="mt-3">
+        <BTabs v-if="!errorMessage" class="mt-3">
             <BTab title-link-class="collection-edit-attributes-nav" @click="updateInfoMessage('')">
                 <template v-slot:title>
                     <FontAwesomeIcon :icon="faBars" class="mr-1" />
diff --git a/client/src/components/History/CurrentCollection/CollectionPanel.vue b/client/src/components/History/CurrentCollection/CollectionPanel.vue
index 7f6f211d6b20..ea99582f77d9 100644
--- a/client/src/components/History/CurrentCollection/CollectionPanel.vue
+++ b/client/src/components/History/CurrentCollection/CollectionPanel.vue
@@ -8,10 +8,12 @@ import { canMutateHistory, isCollectionElement, isHDCA } from "@/api";
 import ExpandedItems from "@/components/History/Content/ExpandedItems";
 import { updateContentFields } from "@/components/History/model/queries";
 import { useCollectionElementsStore } from "@/stores/collectionElementsStore";
+import { errorMessageAsString } from "@/utils/simple-error";
 
 import CollectionDetails from "./CollectionDetails.vue";
 import CollectionNavigation from "./CollectionNavigation.vue";
 import CollectionOperations from "./CollectionOperations.vue";
+import Alert from "@/components/Alert.vue";
 import ContentItem from "@/components/History/Content/ContentItem.vue";
 import ListingLayout from "@/components/History/Layout/ListingLayout.vue";
 
@@ -54,6 +56,7 @@ watch(
 
 const collectionElements = computed(() => collectionElementsStore.getCollectionElements(dsc.value) ?? []);
 const loading = computed(() => collectionElementsStore.isLoadingCollectionElements(dsc.value));
+const error = computed(() => collectionElementsStore.hasLoadingCollectionElementsError(dsc.value));
 const jobState = computed(() => ("job_state_summary" in dsc.value ? dsc.value.job_state_summary : undefined));
 const populatedStateMsg = computed(() =>
     "populated_state_message" in dsc.value ? dsc.value.populated_state_message : undefined
@@ -120,7 +123,10 @@ watch(
 </script>
 
 <template>
-    <ExpandedItems v-slot="{ isExpanded, setExpanded }" :scope-key="dsc.id" :get-item-key="getItemKey">
+    <Alert v-if="error" variant="error">
+        {{ errorMessageAsString(error) }}
+    </Alert>
+    <ExpandedItems v-else v-slot="{ isExpanded, setExpanded }" :scope-key="dsc.id" :get-item-key="getItemKey">
         <section class="dataset-collection-panel w-100 d-flex flex-column">
             <section>
                 <CollectionNavigation
diff --git a/client/src/components/JobParameters/JobParametersArrayValue.vue b/client/src/components/JobParameters/JobParametersArrayValue.vue
index 31be3694434a..014d0e6d12de 100644
--- a/client/src/components/JobParameters/JobParametersArrayValue.vue
+++ b/client/src/components/JobParameters/JobParametersArrayValue.vue
@@ -1,8 +1,9 @@
 <template>
     <div>
         <div v-for="(elVal, pvIndex) in parameter_value" :key="pvIndex">
+            <span v-if="elVal === null">No input provided</span>
             <GenericHistoryItem
-                v-if="['hda', 'hdca', 'dce'].includes(elVal.src)"
+                v-else-if="['hda', 'hdca', 'dce'].includes(elVal.src)"
                 :item-id="elVal.id"
                 :item-src="elVal.src" />
             <span v-else> {{ elVal.hid }}: {{ elVal.name }} </span>
diff --git a/client/src/components/Workflow/Run/WorkflowStorageConfiguration.vue b/client/src/components/Workflow/Run/WorkflowStorageConfiguration.vue
index d67dc2b5a191..893ecc310dcd 100644
--- a/client/src/components/Workflow/Run/WorkflowStorageConfiguration.vue
+++ b/client/src/components/Workflow/Run/WorkflowStorageConfiguration.vue
@@ -91,7 +91,7 @@ export default {
             return `Invocation ${this.preferredOrEmptyString} Storage Location`;
         },
         intermediateModalTitle() {
-            return `Invocation {{ preferredOrEmptyString }} Storage Location (Intermediate Datasets)`;
+            return `Invocation ${this.preferredOrEmptyString} Storage Location (Intermediate Datasets)`;
         },
         suffixPrimary() {
             if (this.splitObjectStore) {
diff --git a/client/src/composables/keyedCache.ts b/client/src/composables/keyedCache.ts
index 6245f797224a..9f73d5b55b00 100644
--- a/client/src/composables/keyedCache.ts
+++ b/client/src/composables/keyedCache.ts
@@ -43,6 +43,7 @@ export function useKeyedCache<T>(
 ) {
     const storedItems = ref<{ [key: string]: T }>({});
     const loadingItem = ref<{ [key: string]: boolean }>({});
+    const loadingErrors = ref<{ [key: string]: Error }>({});
 
     const getItemById = computed(() => {
         return (id: string) => {
@@ -67,10 +68,17 @@ export function useKeyedCache<T>(
         };
     });
 
+    const hasItemLoadError = computed(() => {
+        return (id: string) => {
+            return loadingErrors.value[id] ?? null;
+        };
+    });
+
     async function fetchItemById(params: FetchParams) {
         const itemId = params.id;
         const isAlreadyLoading = loadingItem.value[itemId] ?? false;
-        if (isAlreadyLoading) {
+        const failedLoading = loadingErrors.value[itemId];
+        if (isAlreadyLoading || failedLoading) {
             return;
         }
         set(loadingItem.value, itemId, true);
@@ -79,6 +87,8 @@ export function useKeyedCache<T>(
             const item = await fetchItem({ id: itemId });
             set(storedItems.value, itemId, item);
             return item;
+        } catch (error) {
+            set(loadingErrors.value, itemId, error);
         } finally {
             del(loadingItem.value, itemId);
         }
@@ -98,6 +108,10 @@ export function useKeyedCache<T>(
         /**
          * A computed function that returns true if the item with the given id is currently being fetched.
          */
+        hasItemLoadError,
+        /**
+         * A computed function holding errors
+         */
         isLoadingItem,
         /**
          * Fetches the item with the given id from the server.
diff --git a/client/src/stores/collectionAttributesStore.ts b/client/src/stores/collectionAttributesStore.ts
index 7ed0b89ed5fc..c5741ae31c05 100644
--- a/client/src/stores/collectionAttributesStore.ts
+++ b/client/src/stores/collectionAttributesStore.ts
@@ -15,11 +15,13 @@ export const useCollectionAttributesStore = defineStore("collectionAttributesSto
         return data;
     }
 
-    const { storedItems, getItemById, isLoadingItem } = useKeyedCache<DatasetCollectionAttributes>(fetchAttributes);
+    const { storedItems, getItemById, isLoadingItem, hasItemLoadError } =
+        useKeyedCache<DatasetCollectionAttributes>(fetchAttributes);
 
     return {
         storedAttributes: storedItems,
         getAttributes: getItemById,
         isLoadingAttributes: isLoadingItem,
+        hasItemLoadError: hasItemLoadError,
     };
 });
diff --git a/client/src/stores/collectionElementsStore.ts b/client/src/stores/collectionElementsStore.ts
index 1c91623f173b..16c2abfb074f 100644
--- a/client/src/stores/collectionElementsStore.ts
+++ b/client/src/stores/collectionElementsStore.ts
@@ -36,6 +36,7 @@ const FETCH_LIMIT = 50;
 export const useCollectionElementsStore = defineStore("collectionElementsStore", () => {
     const storedCollections = ref<{ [key: string]: HDCASummary }>({});
     const loadingCollectionElements = ref<{ [key: string]: boolean }>({});
+    const loadingCollectionElementsErrors = ref<{ [key: string]: Error }>({});
     const storedCollectionElements = ref<{ [key: string]: DCEEntry[] }>({});
 
     /**
@@ -62,6 +63,12 @@ export const useCollectionElementsStore = defineStore("collectionElementsStore",
         };
     });
 
+    const hasLoadingCollectionElementsError = computed(() => {
+        return (collection: CollectionEntry) => {
+            return loadingCollectionElementsErrors.value[getCollectionKey(collection) ?? false];
+        };
+    });
+
     type FetchParams = {
         storedElements: DCEEntry[];
         collection: CollectionEntry;
@@ -105,6 +112,8 @@ export const useCollectionElementsStore = defineStore("collectionElementsStore",
             });
 
             return { fetchedElements, elementOffset: offset };
+        } catch (error) {
+            set(loadingCollectionElementsErrors.value, collectionKey, error);
         } finally {
             del(loadingCollectionElements.value, collectionKey);
         }
@@ -161,7 +170,7 @@ export const useCollectionElementsStore = defineStore("collectionElementsStore",
     /** Returns collection from storedCollections, will load collection if not in store */
     const getCollectionById = computed(() => {
         return (collectionId: string) => {
-            if (!storedCollections.value[collectionId]) {
+            if (!storedCollections.value[collectionId] && !loadingCollectionElementsErrors.value[collectionId]) {
                 // TODO: Try to remove this as it can cause computed side effects (use keyedCache in this store instead?)
                 fetchCollection({ id: collectionId });
             }
@@ -175,6 +184,8 @@ export const useCollectionElementsStore = defineStore("collectionElementsStore",
             const collection = await fetchCollectionDetails({ id: params.id });
             set(storedCollections.value, collection.id, collection);
             return collection;
+        } catch (error) {
+            set(loadingCollectionElementsErrors.value, params.id, error);
         } finally {
             del(loadingCollectionElements.value, params.id);
         }
@@ -202,6 +213,8 @@ export const useCollectionElementsStore = defineStore("collectionElementsStore",
         storedCollectionElements,
         getCollectionElements,
         isLoadingCollectionElements,
+        hasLoadingCollectionElementsError,
+        loadingCollectionElementsErrors,
         getCollectionById,
         fetchCollection,
         invalidateCollectionElements,
diff --git a/lib/galaxy/managers/jobs.py b/lib/galaxy/managers/jobs.py
index 546085b26a2e..98cdf2408cb6 100644
--- a/lib/galaxy/managers/jobs.py
+++ b/lib/galaxy/managers/jobs.py
@@ -5,10 +5,12 @@
     datetime,
 )
 from typing import (
+    Any,
     cast,
     Dict,
     List,
     Optional,
+    Union,
 )
 
 import sqlalchemy
@@ -989,16 +991,17 @@ def inputs_recursive(input_params, param_values, depth=1, upgrade_messages=None)
                     or input.type == "data_collection"
                     or isinstance(input_value, model.HistoryDatasetAssociation)
                 ):
-                    value = []
+                    value: List[Union[Dict[str, Any], None]] = []
                     for element in listify(input_value):
-                        element_id = element.id
                         if isinstance(element, model.HistoryDatasetAssociation):
                             hda = element
-                            value.append({"src": "hda", "id": element_id, "hid": hda.hid, "name": hda.name})
+                            value.append({"src": "hda", "id": element.id, "hid": hda.hid, "name": hda.name})
                         elif isinstance(element, model.DatasetCollectionElement):
-                            value.append({"src": "dce", "id": element_id, "name": element.element_identifier})
+                            value.append({"src": "dce", "id": element.id, "name": element.element_identifier})
                         elif isinstance(element, model.HistoryDatasetCollectionAssociation):
-                            value.append({"src": "hdca", "id": element_id, "hid": element.hid, "name": element.name})
+                            value.append({"src": "hdca", "id": element.id, "hid": element.hid, "name": element.name})
+                        elif element is None:
+                            value.append(None)
                         else:
                             raise Exception(
                                 f"Unhandled data input parameter type encountered {element.__class__.__name__}"
diff --git a/lib/galaxy/schema/jobs.py b/lib/galaxy/schema/jobs.py
index fe6316262983..ec7a971a3614 100644
--- a/lib/galaxy/schema/jobs.py
+++ b/lib/galaxy/schema/jobs.py
@@ -223,7 +223,7 @@ class JobParameter(Model):
         title="Depth",
         description="The depth of the job parameter.",
     )
-    value: Optional[Union[List[EncodedJobParameterHistoryItem], float, int, bool, str]] = Field(
+    value: Optional[Union[List[Optional[EncodedJobParameterHistoryItem]], float, int, bool, str]] = Field(
         default=None, title="Value", description="The values of the job parameter", union_mode="left_to_right"
     )
     notes: Optional[str] = Field(default=None, title="Notes", description="Notes associated with the job parameter.")
diff --git a/lib/galaxy/tools/actions/__init__.py b/lib/galaxy/tools/actions/__init__.py
index 989ab5a6ad45..0623e354990b 100644
--- a/lib/galaxy/tools/actions/__init__.py
+++ b/lib/galaxy/tools/actions/__init__.py
@@ -693,6 +693,7 @@ def handle_output(name, output, hidden=None):
                 output_collection.mark_as_populated()
             for hdca in output_collections.out_collection_instances.values():
                 hdca.visible = False
+                hdca.collection.mark_as_populated()
             object_store_populator = ObjectStorePopulator(trans.app, trans.user)
             for data in out_data.values():
                 data.set_skipped(object_store_populator)
diff --git a/lib/galaxy/tools/search/__init__.py b/lib/galaxy/tools/search/__init__.py
index 3fcce2caab42..9fa0c24baff4 100644
--- a/lib/galaxy/tools/search/__init__.py
+++ b/lib/galaxy/tools/search/__init__.py
@@ -71,8 +71,7 @@
 
 def get_or_create_index(index_dir, schema):
     """Get or create a reference to the index."""
-    if not os.path.exists(index_dir):
-        os.makedirs(index_dir)
+    os.makedirs(index_dir, exist_ok=True)
     if index.exists_in(index_dir):
         idx = index.open_dir(index_dir)
         if idx.schema == schema:
diff --git a/lib/galaxy_test/api/test_workflows.py b/lib/galaxy_test/api/test_workflows.py
index d334e15b8cbf..0b3b38de88fd 100644
--- a/lib/galaxy_test/api/test_workflows.py
+++ b/lib/galaxy_test/api/test_workflows.py
@@ -2425,6 +2425,30 @@ def test_run_nested_conditional_workflow_steps(self):
                 if step["workflow_step_label"] == "cat1":
                     assert sum(1 for j in step["jobs"] if j["state"] == "skipped") == 1
 
+    def test_run_workflow_conditional_subworkflow_step_with_hdca_creation(self):
+        # Regression test, ensures scheduling proceeds even if a skipped step creates a collection
+        with self.dataset_populator.test_history() as history_id:
+            self._run_workflow(
+                """
+class: GalaxyWorkflow
+inputs: []
+steps:
+  conditional_subworkflow_step:
+    when: $(false)
+    run:
+      class: GalaxyWorkflow
+      inputs: []
+      steps:
+        create_collection:
+          tool_id: create_input_collection
+        flatten_collection:
+          tool_id: cat_list
+          in:
+            input1: create_collection/output
+                           """,
+                history_id=history_id,
+            )
+
     def test_run_workflow_conditional_step_map_over_expression_tool(self):
         with self.dataset_populator.test_history() as history_id:
             summary = self._run_workflow(
diff --git a/lib/galaxy_test/base/populators.py b/lib/galaxy_test/base/populators.py
index ef71ec8d6132..1104e94b1dbf 100644
--- a/lib/galaxy_test/base/populators.py
+++ b/lib/galaxy_test/base/populators.py
@@ -1770,7 +1770,11 @@ def upload_yaml_workflow(self, yaml_content: YamlContentT, **kwds) -> str:
         return workflow_id
 
     def wait_for_invocation(
-        self, workflow_id: str, invocation_id: str, timeout: timeout_type = DEFAULT_TIMEOUT, assert_ok: bool = True
+        self,
+        workflow_id: Optional[str],
+        invocation_id: str,
+        timeout: timeout_type = DEFAULT_TIMEOUT,
+        assert_ok: bool = True,
     ) -> str:
         url = f"invocations/{invocation_id}"
 
@@ -1818,7 +1822,7 @@ def invocation_count():
 
     def wait_for_workflow(
         self,
-        workflow_id: str,
+        workflow_id: Optional[str],
         invocation_id: str,
         history_id: str,
         assert_ok: bool = True,
@@ -1827,6 +1831,9 @@ def wait_for_workflow(
         """Wait for a workflow invocation to completely schedule and then history
         to be complete."""
         self.wait_for_invocation(workflow_id, invocation_id, timeout=timeout, assert_ok=assert_ok)
+        for step in self.get_invocation(invocation_id)["steps"]:
+            if step["subworkflow_invocation_id"]:
+                self.wait_for_invocation(None, step["subworkflow_invocation_id"], timeout=timeout, assert_ok=assert_ok)
         self.dataset_populator.wait_for_history_jobs(history_id, assert_ok=assert_ok, timeout=timeout)
 
     def get_invocation(self, invocation_id, step_details=False):