From 773cb7424c2df8e3bd6389e048bad11be1b66d3a Mon Sep 17 00:00:00 2001
From: steinmn <46349253+steinmn@users.noreply.github.com>
Date: Sun, 23 Nov 2025 14:43:44 +0100
Subject: [PATCH] Translatable error msg to frontend if new dashboard url
 already in use (#153501)

---
 .../components/lovelace/dashboard.py          |  6 +++-
 .../components/lovelace/strings.json          |  5 ++++
 tests/components/lovelace/test_dashboard.py   | 28 ++++++++++++++++---
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/homeassistant/components/lovelace/dashboard.py b/homeassistant/components/lovelace/dashboard.py
index 4faf4f15b08c..41e82291e44f 100644
--- a/homeassistant/components/lovelace/dashboard.py
+++ b/homeassistant/components/lovelace/dashboard.py
@@ -287,7 +287,11 @@ class DashboardsCollection(collection.DictStorageCollection):
             raise vol.Invalid("Url path needs to contain a hyphen (-)")
 
         if url_path in self.hass.data[DATA_PANELS]:
-            raise vol.Invalid("Panel url path needs to be unique")
+            raise HomeAssistantError(
+                translation_domain=DOMAIN,
+                translation_key="url_already_exists",
+                translation_placeholders={"url": url_path},
+            )
 
         return self.CREATE_SCHEMA(data)  # type: ignore[no-any-return]
 
diff --git a/homeassistant/components/lovelace/strings.json b/homeassistant/components/lovelace/strings.json
index 98b5877cb50f..704e864c5678 100644
--- a/homeassistant/components/lovelace/strings.json
+++ b/homeassistant/components/lovelace/strings.json
@@ -1,4 +1,9 @@
 {
+  "exceptions": {
+    "url_already_exists": {
+      "message": "The URL \"{url}\" is already in use. Please choose a different one."
+    }
+  },
   "services": {
     "reload_resources": {
       "description": "Reloads dashboard resources from the YAML-configuration.",
diff --git a/tests/components/lovelace/test_dashboard.py b/tests/components/lovelace/test_dashboard.py
index 3a01e20c1fbc..5950fb7d62ac 100644
--- a/tests/components/lovelace/test_dashboard.py
+++ b/tests/components/lovelace/test_dashboard.py
@@ -374,7 +374,7 @@ async def test_storage_dashboards(
     assert response["success"]
     assert response["result"] == []
 
-    # Add a wrong dashboard
+    # Add a wrong dashboard (no hyphen)
     await client.send_json(
         {
             "id": 6,
@@ -484,16 +484,36 @@ async def test_storage_dashboards(
     assert response["result"][0]["show_in_sidebar"] is False
     assert response["result"][0]["require_admin"] is False
 
-    # Add dashboard with existing url path
+    # Add a wrong dashboard (missing title)
     await client.send_json(
-        {"id": 14, "type": "lovelace/dashboards/create", "url_path": "created-url-path"}
+        {
+            "id": 14,
+            "type": "lovelace/dashboards/create",
+            "url_path": "path",
+        }
     )
     response = await client.receive_json()
     assert not response["success"]
+    assert response["error"]["code"] == "invalid_format"
+
+    # Add dashboard with existing url path
+    await client.send_json(
+        {
+            "id": 15,
+            "type": "lovelace/dashboards/create",
+            "url_path": "created-url-path",
+            "title": "Another title",
+        }
+    )
+    response = await client.receive_json()
+    assert not response["success"]
+    assert response["error"]["code"] == "home_assistant_error"
+    assert response["error"]["translation_key"] == "url_already_exists"
+    assert response["error"]["translation_placeholders"]["url"] == "created-url-path"
 
     # Delete dashboards
     await client.send_json(
-        {"id": 15, "type": "lovelace/dashboards/delete", "dashboard_id": dashboard_id}
+        {"id": 16, "type": "lovelace/dashboards/delete", "dashboard_id": dashboard_id}
     )
     response = await client.receive_json()
     assert response["success"]