diff --git a/changelog.d/1241-street-level-panel-cuts.md b/changelog.d/1241-street-level-panel-cuts.md
index d10d0c613..1dd9dc5f5 100644
--- a/changelog.d/1241-street-level-panel-cuts.md
+++ b/changelog.d/1241-street-level-panel-cuts.md
@@ -1,5 +1,5 @@
 - Street Level panel: SINCE is a dropdown of its nine windows (the tooltip
   names the cut-off date), IMAGERY and FIT / FILL are plain toggle buttons,
-  and the panel opens by itself only when a photo opens or fails to, no
-  longer when the layer is switched on. FIT / FILL starts at FIT each
-  session (gekh, #1241).
+  and the panel opens by itself only when a photo opens or a click fails to
+  load one, no longer when the layer is switched on. FIT / FILL starts at
+  FIT each session (gekh, #1241).
diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index 22df1c290..dc4b30d2c 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -3539,8 +3539,9 @@ image; FIT/FILL starts at FIT each session. IMAGERY and FIT/FILL are rows of
 toggle buttons (`aria-pressed`), each its own tab stop. SINCE is a select of
 the nine windows; a link's day count between them gets its own option, and
 the tooltip names the cut-off date. The panel opens by itself only when a
-photo opens or fails to (a click on the map or a line would otherwise load
-it, or its error, out of sight), never when the layer is switched on.
+photo opens, or a click fails to open one or to load its sequence (the
+result, or its error, would otherwise be out of sight), never when the layer
+is switched on.
 
 MapillaryJS loads on the first photo. Opening one frames it with a single
 camera flight through the application's deferred navigation (`begin` /
diff --git a/src/ui/streetLevelControls.js b/src/ui/streetLevelControls.js
index 0b65b2583..e9bb3acfc 100644
--- a/src/ui/streetLevelControls.js
+++ b/src/ui/streetLevelControls.js
@@ -29,7 +29,7 @@ export class StreetLevelControls {
     this._state = null;
     this._view = null;
     this._wasOpen = false;
-    /** The open error last shown, so the same one never reopens the panel. */
+    /** The error last shown: the same one never reopens the panel. */
     this._streetError = null;
     /** The SINCE option for a day count between the stops, while one is set. */
     this._customSince = null;
@@ -432,17 +432,20 @@ export class StreetLevelControls {
   }
 
   /**
-   * Open the panel when an image opens, or fails to (a click on the map or a
-   * line would otherwise load it, or its error, out of sight). Never
-   * persisted: the stored collapse state stays the user's own choice.
+   * Open the panel when an image opens, or when a click fails to open one or
+   * to load its sequence (the result, or its error, would otherwise be out of
+   * sight). Never persisted: the stored collapse state stays the user's own
+   * choice.
    */
   _reactToTransitions(view) {
     // Other size changes reach the viewer through the ResizeObserver; opening
     // asks for one resize because the element may not have a size yet.
     const open = view.viewer.open;
-    // A photo that failed to open (a line or ground click, OPEN) says why in
-    // the panel: it opens for that too, or the click would seem to do nothing.
-    const error = this._state?.street?.error || null;
+    // A photo that failed to open (a line or ground click, OPEN), or a
+    // Mapillary line whose sequence failed to load, says why in the panel:
+    // it opens for that too, or the click would seem to do nothing.
+    const error =
+      this._state?.street?.error || this._state?.sequence?.error || null;
     if ((open && !this._wasOpen) || (error && error !== this._streetError))
       this.setCollapsed(false, { persist: false });
     this._wasOpen = open;
diff --git a/src/ui/streetLevelControls.test.mjs b/src/ui/streetLevelControls.test.mjs
index f7d2f98cd..dd6b6c196 100644
--- a/src/ui/streetLevelControls.test.mjs
+++ b/src/ui/streetLevelControls.test.mjs
@@ -426,6 +426,7 @@ function uiState({
   renderMode = 'letterbox',
   keyRequired = false,
   streetError = null,
+  sequenceError = null,
 } = {}) {
   return {
     enabled,
@@ -434,7 +435,12 @@ function uiState({
     keyRejected: false,
     filter: { pano, sinceDays },
     coverage: { count: 3, loading: false, hint: '', error: null },
-    sequence: { selectedId: null, images: 0, loading: false },
+    sequence: {
+      selectedId: null,
+      images: 0,
+      loading: false,
+      error: sequenceError,
+    },
     street: {
       open,
       loading: false,
@@ -803,6 +809,18 @@ test('a photo that fails to open opens the panel too, so its error shows', () =>
     controls.destroy();
   }));
 
+test('a sequence that fails to load opens the panel, so its error shows', () =>
+  withDom(async (dom) => {
+    const { layer, calls, controls } = stubPanel(dom, uiState());
+    // A Mapillary line click whose sequence lookup the Graph API refused.
+    layer.publish(uiState({ sequenceError: 'Mapillary did not answer' }));
+    assert.deepEqual(calls.collapsed, [[false, { persist: false }]]);
+    assert.equal(dom.root.querySelector('#sl-error').hidden, false);
+    layer.publish(uiState({ sequenceError: 'Mapillary did not answer' }));
+    assert.equal(calls.collapsed.length, 1, 'the same error opens it once');
+    controls.destroy();
+  }));
+
 test('FIT / FILL show the selected render mode (P3)', () =>
   withDom(async (dom) => {
     const { layer, controls } = stubPanel(dom, uiState({ open: true }));