diff --git a/web/sections/CollectionsPanel.tsx b/web/sections/CollectionsPanel.tsx
index 606ec7f..458409c 100644
--- a/web/sections/CollectionsPanel.tsx
+++ b/web/sections/CollectionsPanel.tsx
@@ -61,15 +61,42 @@ export const CollectionsPanel = () => {
     void load();
   }, [load]);
 
-  // The folder's contents, re-read when the selection moves. Null while nothing is chosen, so the
+  /*
+    A selection naming something that is not there any more.
+
+    The id lives in the URL, so it outlives the row: delete a collection with it open, reload, and the
+    address still asks for it. Left alone that became a 404 from the media fetch, rendered as "Not
+    found" over a panel that was otherwise working — an error about the URL, phrased as an error about
+    the server.
+
+    Dropped rather than reported. There is nothing for anybody to do about it and the correct state is
+    simply "nothing selected".
+  */
+  useEffect(() => {
+    if (!collections || !selectedId) return;
+    if (collections.some((one) => one.id === selectedId)) return;
+    setParams(
+      (current) => {
+        const next = new URLSearchParams(current);
+        next.delete('collection');
+        return next;
+      },
+      { replace: true },
+    );
+  }, [collections, selectedId, setParams]);
+
+  // The gallery's photographs, re-read when the selection moves. Null while nothing is chosen, so the
   // empty state and "still loading" are not the same thing.
   useEffect(() => {
-    if (!selectedId) {
+    if (!selectedId || !selected) {
       setPhotos(null);
       return;
     }
     let alive = true;
     setPhotos(null);
+    // Cleared here rather than only on success: an error from the last selection has nothing to say
+    // about this one, and leaving it up reads as the new one having failed too.
+    setError(null);
     void clientRef.current
       .get<{ data: CollectionPhoto[] }>(`/fofos-admin/collections/${selectedId}/media`)
       .then((response) => alive && setPhotos(response.data))
@@ -77,7 +104,7 @@ export const CollectionsPanel = () => {
     return () => {
       alive = false;
     };
-  }, [selectedId]);
+  }, [selectedId, selected]);
 
   /*
     The fields, in the editor column — a SIBLING panel, so they are announced rather than rendered.