diff --git a/intermediate/indexing/why-an-index.ipynb b/intermediate/indexing/why-an-index.ipynb
index 3123f3d1..487126ff 100644
--- a/intermediate/indexing/why-an-index.ipynb
+++ b/intermediate/indexing/why-an-index.ipynb
@@ -4,6 +4,17 @@
    "cell_type": "markdown",
    "id": "0",
    "metadata": {},
+   "source": [
+    "```{admonition} This notebook is currently broken\n",
+    ":class: warning\n",
+    "This notebook has known issues and may not execute correctly. See [xarray-contrib/xarray-tutorial#376](https://github.com/xarray-contrib/xarray-tutorial/issues/376) for details and progress.\n",
+    "```"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "1",
+   "metadata": {},
    "source": [
     "# Why does xarray need an *index*? \n",
     "\n",
@@ -41,7 +52,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "1",
+   "id": "2",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -74,7 +85,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "2",
+   "id": "3",
    "metadata": {},
    "source": [
     "## 1. Built-in indexes \n",
@@ -86,7 +97,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "3",
+   "id": "4",
    "metadata": {},
    "source": [
     "## 1.1 A coordinate is just an array of labels\n",
@@ -99,7 +110,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4",
+   "id": "5",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -118,7 +129,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "5",
+   "id": "6",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -127,7 +138,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "6",
+   "id": "7",
    "metadata": {},
    "source": [
     "\n",
@@ -139,7 +150,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "7",
+   "id": "8",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -150,7 +161,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "8",
+   "id": "9",
    "metadata": {},
    "source": [
     "### Let the index do it"
@@ -159,7 +170,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "9",
+   "id": "10",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -178,7 +189,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "10",
+   "id": "11",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -196,7 +207,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "11",
+   "id": "12",
    "metadata": {},
    "source": [
     "### Recap: the 1‑D index\n",
@@ -212,7 +223,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "12",
+   "id": "13",
    "metadata": {},
    "source": [
     "## 1.2 Generated, not stored: `RangeIndex`\n",
@@ -232,7 +243,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "13",
+   "id": "14",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -244,7 +255,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "14",
+   "id": "15",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -254,7 +265,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "15",
+   "id": "16",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -265,7 +276,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "16",
+   "id": "17",
    "metadata": {},
    "source": [
     "The labels never materialize unless we request them, so we didn't run out of memory."
@@ -273,7 +284,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "17",
+   "id": "18",
    "metadata": {},
    "source": [
     "## 1.3 Slicing in space *and* time\n",
@@ -286,7 +297,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "18",
+   "id": "19",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -316,7 +327,7 @@
     }
    },
    "cell_type": "markdown",
-   "id": "19",
+   "id": "20",
    "metadata": {},
    "source": [
     "## 2. A metal ring: when the axis wraps around\n",
@@ -338,7 +349,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "20",
+   "id": "21",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -364,7 +375,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "21",
+   "id": "22",
    "metadata": {
     "tags": [
      "hide-input"
@@ -403,7 +414,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "22",
+   "id": "23",
    "metadata": {},
    "source": [
     "### The problem! \n",
@@ -414,7 +425,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "23",
+   "id": "24",
    "metadata": {
     "tags": [
      "hide-input"
@@ -441,7 +452,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "24",
+   "id": "25",
    "metadata": {},
    "source": [
     "## 2.1 📝 Write your own: a `PeriodicIndex`\n",
@@ -487,7 +498,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "25",
+   "id": "26",
    "metadata": {
     "tags": [
      "hide-input"
@@ -524,7 +535,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "26",
+   "id": "27",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -537,7 +548,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "27",
+   "id": "28",
    "metadata": {},
    "source": [
     "### Does your index fix the -180, 180 issue?\n",
@@ -547,7 +558,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "28",
+   "id": "29",
    "metadata": {
     "tags": [
      "hide-input"
@@ -574,7 +585,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "29",
+   "id": "30",
    "metadata": {},
    "source": [
     "## 3. Build your own: a `CoordinateTransform` (step 1 of 2 — a 1-D ruler)\n",
@@ -614,7 +625,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "30",
+   "id": "31",
    "metadata": {
     "tags": [
      "hide-input"
@@ -645,7 +656,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "31",
+   "id": "32",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -663,7 +674,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "32",
+   "id": "33",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -685,7 +696,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "33",
+   "id": "34",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -697,7 +708,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "34",
+   "id": "35",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -710,7 +721,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "35",
+   "id": "36",
    "metadata": {},
    "source": [
     "## 4. A nonlinear warp (a fisheye lens) 🔍\n",
@@ -727,7 +738,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "36",
+   "id": "37",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -763,7 +774,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "37",
+   "id": "38",
    "metadata": {
     "tags": [
      "hide-input"
@@ -789,7 +800,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "38",
+   "id": "39",
    "metadata": {},
    "source": [
     "### Can xarray handle the undistorted coordinates\n"
@@ -798,7 +809,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "39",
+   "id": "40",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -817,7 +828,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "40",
+   "id": "41",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -826,7 +837,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "41",
+   "id": "42",
    "metadata": {},
    "source": [
     "**It breaks.** The standard index can't handle a 2-D coordinate.\n",
@@ -835,7 +846,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "42",
+   "id": "43",
    "metadata": {},
    "source": [
     "### The better fix: A custom Index!\n",
@@ -847,7 +858,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "43",
+   "id": "44",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -897,7 +908,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "44",
+   "id": "45",
    "metadata": {
     "tags": [
      "hide-input"
@@ -920,7 +931,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "45",
+   "id": "46",
    "metadata": {
     "tags": [
      "hide-input"
@@ -949,7 +960,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "46",
+   "id": "47",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -976,7 +987,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "47",
+   "id": "48",
    "metadata": {},
    "source": [
     "https://xarray-indexes.readthedocs.io/"
@@ -985,13 +996,16 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "48",
+   "id": "49",
    "metadata": {},
    "outputs": [],
    "source": []
   }
  ],
  "metadata": {
+  "execution": {
+   "allow_errors": true
+  },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",