diff --git a/frontend/src/app/main/thumbnail_renderer.cljs b/frontend/src/app/main/thumbnail_renderer.cljs
index 54c668af7..db159e7b9 100644
--- a/frontend/src/app/main/thumbnail_renderer.cljs
+++ b/frontend/src/app/main/thumbnail_renderer.cljs
@@ -78,7 +78,7 @@
          (rx/mapcat (fn [msg]
                       (case (unchecked-get msg "type")
                         "success" (rx/of (unchecked-get msg "payload"))
-                        "failure" (rx/throw (unchecked-get msg "payload")))))
+                        "failure" (rx/throw (js/Error. (unchecked-get msg "payload"))))))
          (rx/take 1))))
 
 (defn init!
@@ -88,6 +88,6 @@
     (dom/set-attribute! iframe "src" origin)
     (dom/set-attribute! iframe "hidden" true)
     (dom/append-child! js/document.body iframe)
-
+    (.addEventListener js/window "message" on-message)
     (set! instance iframe)
-    (.addEventListener js/window "message" on-message)))
+    ))
diff --git a/frontend/src/app/main/ui/dashboard/grid.cljs b/frontend/src/app/main/ui/dashboard/grid.cljs
index 27fc812ad..1e79a506f 100644
--- a/frontend/src/app/main/ui/dashboard/grid.cljs
+++ b/frontend/src/app/main/ui/dashboard/grid.cljs
@@ -76,7 +76,12 @@
       (when (and visible? (not thumbnail-uri))
         (->> (ask-for-thumbnail file-id revn)
              (rx/subs (fn [url]
-                        (st/emit! (dd/set-file-thumbnail file-id url)))))))
+                        (st/emit! (dd/set-file-thumbnail file-id url)))
+                      (fn [cause]
+                        (log/error :hint "unable to render thumbnail"
+                                   :file-if file-id
+                                   :revn revn
+                                   :message (ex-message cause)))))))
 
     [:div.grid-item-th
      {:style {:background-color background-color}
diff --git a/frontend/src/app/thumbnail_renderer.cljs b/frontend/src/app/thumbnail_renderer.cljs
index aa6dab25a..987f9565f 100644
--- a/frontend/src/app/thumbnail_renderer.cljs
+++ b/frontend/src/app/thumbnail_renderer.cljs
@@ -229,8 +229,8 @@
 
 (defn- send-failure!
   "Sends a failure message."
-  [id payload]
-  (send-answer! id "failure" payload))
+  [id cause]
+  (send-answer! id "failure" (ex-message cause)))
 
 (defn- send-ready!
   "Sends a ready message."