diff --git a/src/App.vue b/src/App.vue
index b6d1044d59..1ac1f6ee4d 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -124,13 +124,13 @@ export default {
       }
 
       const personId = eventData.person_id
-      const selectedTaskIds = [eventData.task_id]
+      const taskIds = [eventData.task_id]
 
       // for entity lists
       if (assign) {
-        this.$store.commit('ASSIGN_TASKS', { selectedTaskIds, personId })
+        this.$store.commit('ASSIGN_TASKS', { taskIds, personId })
       } else {
-        this.$store.commit('UNASSIGN_TASKS', selectedTaskIds)
+        this.$store.commit('UNASSIGN_TASKS', taskIds)
       }
     },
 
diff --git a/src/components/tops/ActionPanel.vue b/src/components/tops/ActionPanel.vue
index 6879a89e3c..68e0ef93a3 100644
--- a/src/components/tops/ActionPanel.vue
+++ b/src/components/tops/ActionPanel.vue
@@ -391,6 +391,14 @@
               {{ $t('tasks.assignation_disclaimer') }}
             </router-link>
           </div>
+          <div
+            class="flexrow-item mb05 assignation-error"
+            v-if="errors.taskAssignation"
+          >
+            <p class="is-danger has-text-centered">
+              {{ $t('tasks.assignation_error') }}
+            </p>
+          </div>
           <div
             class="flexrow-item is-wide flexrow"
             v-if="
@@ -943,6 +951,7 @@ export default {
       },
       errors: {
         assetDeletion: false,
+        taskAssignation: false,
         taskDeletion: false,
         conceptDeletion: false,
         editDeletion: false,
@@ -1315,10 +1324,12 @@ export default {
             ? this.selectedPersonId
             : this.user.id
         this.loading.assignation = true
+        this.errors.taskAssignation = false
         try {
           await this.assignSelectedTasks({ personId })
           this.$refs['assignation-field']?.clear()
         } catch (err) {
+          this.errors.taskAssignation = true
           console.error(err)
         } finally {
           this.loading.assignation = false
@@ -1789,6 +1800,10 @@ export default {
   overflow-x: auto;
   overflow-y: hidden;
 }
+.is-danger {
+  color: #ff3860;
+  font-style: italic;
+}
 
 .menu-item {
   cursor: pointer;
diff --git a/src/locales/en.js b/src/locales/en.js
index 8d17bf3447..76850703ab 100644
--- a/src/locales/en.js
+++ b/src/locales/en.js
@@ -1718,6 +1718,7 @@ export default {
     assignation_disclaimer: 'If people are missing from the list, it means they are not listed in the team.',
     assign_explaination: 'Select a person to assign...',
     assignation_warning: 'Warning: you won\'t see the result because you are hiding assignments',
+    assignation_error: 'There was a problem assigning this person to the selected tasks. Not all tasks were assigned.',
     back_to_list: 'back to list',
     bigger: 'Widen task panel',
     big_thumbnails: 'Show big thumbnails',
diff --git a/src/store/modules/tasks.js b/src/store/modules/tasks.js
index 189260a6d8..fc7bc6051c 100644
--- a/src/store/modules/tasks.js
+++ b/src/store/modules/tasks.js
@@ -643,8 +643,20 @@ const actions = {
 
   assignSelectedTasks({ commit, state }, { personId, taskIds }) {
     const selectedTaskIds = taskIds || Array.from(state.selectedTasks.keys())
-    return tasksApi.assignTasks(personId, selectedTaskIds).then(() => {
-      commit(ASSIGN_TASKS, { selectedTaskIds, personId })
+    return tasksApi.assignTasks(personId, selectedTaskIds).then(response => {
+      const successfulTaskIds = response.map(task => task.id)
+      const failedTaskIds = selectedTaskIds.filter(
+        taskId => !successfulTaskIds.includes(taskId)
+      )
+      commit(ASSIGN_TASKS, { taskIds: successfulTaskIds, personId })
+      if (failedTaskIds.length) {
+        const error = new Error(
+          `Failed to assign ${failedTaskIds.length} task(s). Task IDs: ${failedTaskIds.join(', ')}`
+        )
+        error.failedTaskIds = failedTaskIds
+        error.successfulTaskIds = successfulTaskIds
+        throw error
+      }
     })
   },
 
@@ -1180,8 +1192,8 @@ const mutations = {
     }
   },
 
-  [ASSIGN_TASKS](state, { selectedTaskIds, personId }) {
-    selectedTaskIds.forEach(taskId => {
+  [ASSIGN_TASKS](state, { taskIds, personId }) {
+    taskIds.forEach(taskId => {
       const task = state.taskMap.get(taskId)
       if (task && !task.assignees.find(assigneeId => assigneeId === personId)) {
         task.assignees.push(personId)
@@ -1190,8 +1202,8 @@ const mutations = {
     })
   },
 
-  [UNASSIGN_TASKS](state, selectedTaskIds) {
-    selectedTaskIds.forEach(taskId => {
+  [UNASSIGN_TASKS](state, taskIds) {
+    taskIds.forEach(taskId => {
       const task = state.taskMap.get(taskId)
       if (task) {
         task.assignees = []