diff --git a/frontend/src/components/admin/user/GroupReplaceModal.vue b/frontend/src/components/admin/user/GroupReplaceModal.vue
index 429826ba3b..3a34274cae 100644
--- a/frontend/src/components/admin/user/GroupReplaceModal.vue
+++ b/frontend/src/components/admin/user/GroupReplaceModal.vue
@@ -80,6 +80,7 @@ import { ref, watch, computed } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { useAppStore } from '@/stores/app'
 import { adminAPI } from '@/api/admin'
+import { extractApiErrorMessage } from '@/utils/apiError'
 import type { AdminUser, AdminGroup } from '@/types'
 import BaseDialog from '@/components/common/BaseDialog.vue'
 import Icon from '@/components/icons/Icon.vue'
@@ -123,6 +124,7 @@ const handleReplace = async () => {
     emit('success')
     emit('close')
   } catch (error) {
+    appStore.showError(extractApiErrorMessage(error, t('common.error')))
     console.error('Failed to replace group:', error)
   } finally {
     submitting.value = false
diff --git a/frontend/src/components/admin/user/__tests__/GroupReplaceModal.spec.ts b/frontend/src/components/admin/user/__tests__/GroupReplaceModal.spec.ts
new file mode 100644
index 0000000000..ab7e3b5704
--- /dev/null
+++ b/frontend/src/components/admin/user/__tests__/GroupReplaceModal.spec.ts
@@ -0,0 +1,58 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { enableAutoUnmount, flushPromises, mount } from '@vue/test-utils'
+import type { AdminGroup, AdminUser } from '@/types'
+import GroupReplaceModal from '../GroupReplaceModal.vue'
+
+const mocks = vi.hoisted(() => ({ replaceGroup: vi.fn(), showError: vi.fn(), showSuccess: vi.fn() }))
+vi.mock('@/api/admin', () => ({ adminAPI: { users: { replaceGroup: mocks.replaceGroup } } }))
+vi.mock('@/stores/app', () => ({ useAppStore: () => mocks }))
+vi.mock('vue-i18n', () => ({ useI18n: () => ({ t: (key: string) => key }) }))
+enableAutoUnmount(afterEach)
+afterEach(() => vi.restoreAllMocks())
+beforeEach(() => {
+  vi.clearAllMocks()
+  vi.spyOn(console, 'error').mockImplementation(() => {})
+})
+
+async function selectGroup() {
+  const wrapper = mount(GroupReplaceModal, {
+    props: {
+      show: true, user: { id: 10 } as AdminUser, oldGroup: { id: 1, name: 'Old' },
+      allGroups: [{ id: 2, name: 'New', status: 'active', is_exclusive: true, subscription_type: 'standard' } as AdminGroup]
+    },
+    global: { stubs: {
+      BaseDialog: { props: ['show'], template: '<div v-if="show"><slot /><slot name="footer" /></div>' }, Icon: true
+    } }
+  })
+  await wrapper.get('input[type="radio"]').setValue()
+  return wrapper
+}
+
+describe('GroupReplaceModal feedback', () => {
+  it.each([
+    [{ message: 'Group is unavailable' }, 'Group is unavailable'],
+    [{ response: { data: { detail: 'Permission denied' } } }, 'Permission denied'],
+    [{}, 'common.error']
+  ])('shows API errors and keeps the dialog available for retry', async (error, message) => {
+    mocks.replaceGroup.mockRejectedValueOnce(error)
+    const wrapper = await selectGroup()
+    await wrapper.get('button.btn-primary').trigger('click')
+    await flushPromises()
+    expect(mocks.showError).toHaveBeenCalledWith(message)
+    expect(wrapper.emitted('success')).toBeUndefined()
+    expect(wrapper.emitted('close')).toBeUndefined()
+    expect(wrapper.get('button.btn-primary').attributes('disabled')).toBeUndefined()
+  })
+
+  it('still reports successful migrations and closes', async () => {
+    mocks.replaceGroup.mockResolvedValueOnce({ migrated_keys: 3 })
+    const wrapper = await selectGroup()
+    await wrapper.get('button.btn-primary').trigger('click')
+    await flushPromises()
+    expect(mocks.replaceGroup).toHaveBeenCalledWith(10, 1, 2)
+    expect(mocks.showSuccess).toHaveBeenCalledWith('admin.users.replaceGroupSuccess')
+    expect(mocks.showError).not.toHaveBeenCalled()
+    expect(wrapper.emitted('success')).toHaveLength(1)
+    expect(wrapper.emitted('close')).toHaveLength(1)
+  })
+})