diff --git a/backend/src/app/http/errors.clj b/backend/src/app/http/errors.clj
index bd40ded1d..fee8f2336 100644
--- a/backend/src/app/http/errors.clj
+++ b/backend/src/app/http/errors.clj
@@ -49,12 +49,20 @@
 
 (defmethod handle-exception :validation
   [err _]
-  (let [data    (ex-data err)
-        explain (us/pretty-explain data)]
-    (yrs/response :status 400
-                  :body   (-> data
-                              (dissoc ::s/problems ::s/value)
-                              (cond-> explain (assoc :explain explain))))))
+  (let [{:keys [code] :as data} (ex-data err)]
+    (cond
+      (= code :spec-validation)
+      (let [explain (us/pretty-explain data)]
+        (yrs/response :status 400
+                      :body   (-> data
+                                  (dissoc ::s/problems ::s/value)
+                                  (cond-> explain (assoc :explain explain)))))
+
+      (= code :request-body-too-large)
+      (yrs/response :status 413 :body data)
+
+      :else
+      (yrs/response :status 400 :body data))))
 
 (defmethod handle-exception :assertion
   [error request]
diff --git a/backend/src/app/http/middleware.clj b/backend/src/app/http/middleware.clj
index bdc997c05..af7f140a8 100644
--- a/backend/src/app/http/middleware.clj
+++ b/backend/src/app/http/middleware.clj
@@ -16,7 +16,10 @@
    [yetti.middleware :as ymw]
    [yetti.request :as yrq]
    [yetti.response :as yrs])
-  (:import java.io.OutputStream))
+  (:import
+   com.fasterxml.jackson.core.io.JsonEOFException
+   io.undertow.server.RequestTooBigException
+   java.io.OutputStream))
 
 (def server-timing
   {:name ::server-timing
@@ -46,16 +49,29 @@
                         (update :params merge params))))
 
                 :else
-                request)))]
+                request)))
+
+          (handle-error [raise cause]
+            (cond
+              (instance? RequestTooBigException cause)
+              (raise (ex/error :type :validation
+                               :code :request-body-too-large
+                               :hint (ex-message cause)))
+
+              (instance? JsonEOFException cause)
+              (raise (ex/error :type :validation
+                               :code :malformed-json
+                               :hint (ex-message cause)))
+              :else
+              (raise cause)))]
 
     (fn [request respond raise]
       (when-let [request (try
                            (process-request request)
-                           (catch Exception cause
-                             (raise (ex/error :type :validation
-                                              :code :malformed-params
-                                              :hint (ex-message cause)
-                                              :cause cause))))]
+                           (catch RuntimeException cause
+                             (handle-error raise (or (.getCause cause) cause)))
+                           (catch Throwable cause
+                             (handle-error raise cause)))]
         (handler request respond raise)))))
 
 (def parse-request
diff --git a/backend/src/app/main.clj b/backend/src/app/main.clj
index df77de7b8..9fe00155e 100644
--- a/backend/src/app/main.clj
+++ b/backend/src/app/main.clj
@@ -20,9 +20,9 @@
     :read-only  (cf/get :database-readonly false)
     :metrics    (ig/ref :app.metrics/metrics)
     :migrations (ig/ref :app.migrations/all)
-    :name :main
-    :min-size (cf/get :database-min-pool-size 0)
-    :max-size (cf/get :database-max-pool-size 30)}
+    :name       :main
+    :min-size   (cf/get :database-min-pool-size 0)
+    :max-size   (cf/get :database-max-pool-size 30)}
 
    ;; Default thread pool for IO operations
    [::default :app.worker/executor]
diff --git a/frontend/src/app/main/errors.cljs b/frontend/src/app/main/errors.cljs
index 549813a40..163f70308 100644
--- a/frontend/src/app/main/errors.cljs
+++ b/frontend/src/app/main/errors.cljs
@@ -7,8 +7,10 @@
 (ns app.main.errors
   "Generic error handling"
   (:require
+   [app.common.data :as d]
    [app.common.data.macros :as dm]
    [app.common.exceptions :as ex]
+   [app.common.pprint :as pp]
    [app.config :as cf]
    [app.main.data.messages :as msg]
    [app.main.data.users :as du]
@@ -17,7 +19,6 @@
    [app.util.i18n :refer [tr]]
    [app.util.router :as rt]
    [app.util.timers :as ts]
-   [fipp.edn :as fpp]
    [potok.core :as ptk]))
 
 (defn on-error
@@ -59,16 +60,15 @@
 (defmethod ptk/handle-error :validation
   [error]
   (ts/schedule
-   (st/emitf
-    (msg/show {:content "Unexpected validation error."
-              :type :error
-              :timeout 3000})))
+   #(st/emit! (msg/show {:content "Validation error"
+                         :type :error
+                         :timeout 3000})))
 
   ;; Print to the console some debug info.
   (js/console.group "Validation Error:")
   (ex/ignoring
    (js/console.info
-    (with-out-str (fpp/pprint (dissoc error :explain)))))
+    (pp/pprint-str (dissoc error :explain))))
 
   (when-let [explain (:explain error)]
     (js/console.group "Spec explain:")
@@ -78,24 +78,46 @@
   (js/console.groupEnd "Validation Error:"))
 
 
+;; All the errors that happens on worker are handled here.
+(defmethod ptk/handle-error :worker-error
+  [{:keys [code data hint] :as error}]
+  (let [hint (or hint (:hint data) (:message data) (d/name code))
+        info (pp/pprint-str (dissoc data :explain))
+        msg  (dm/str "Internal Worker Error: " hint)]
+
+    (ts/schedule
+     #(st/emit!
+       (msg/show {:content "Something wrong has happened (on worker)."
+                  :type :error
+                  :timeout 3000})))
+
+    (js/console.group msg)
+    (js/console.info info)
+
+    (when-let [explain (:explain data)]
+      (js/console.group "Spec explain:")
+      (js/console.log explain)
+      (js/console.groupEnd "Spec explain:"))
+
+    (js/console.groupEnd msg)))
+
+
 ;; Error on parsing an SVG
 ;; TODO: looks unused and deprecated
 (defmethod ptk/handle-error :svg-parser
   [_]
   (ts/schedule
-   (st/emitf
-    (msg/show {:content "SVG is invalid or malformed"
-              :type :error
-              :timeout 3000}))))
+   #(st/emit! (msg/show {:content "SVG is invalid or malformed"
+                         :type :error
+                         :timeout 3000}))))
 
 ;; TODO: should be handled in the event and not as general error handler
 (defmethod ptk/handle-error :comment-error
   [_]
   (ts/schedule
-   (st/emitf
-    (msg/show {:content "There was an error with the comment"
-              :type :error
-              :timeout 3000}))))
+   #(st/emit! (msg/show {:content "There was an error with the comment"
+                         :type :error
+                         :timeout 3000}))))
 
 ;; This is a pure frontend error that can be caused by an active
 ;; assertion (assertion that is preserved on production builds). From
@@ -110,10 +132,9 @@
                         (dm/str cf/public-uri "js/cljs-runtime/" (:file error))
                         (:line error))]
     (ts/schedule
-     (st/emitf
-      (msg/show {:content "Internal error: assertion."
-                 :type :error
-                 :timeout 3000})))
+     #(st/emit! (msg/show {:content "Internal error: assertion."
+                           :type :error
+                           :timeout 3000})))
 
     ;; Print to the console some debugging info
     (js/console.group message)
@@ -139,7 +160,7 @@
 (defmethod ptk/handle-error :server-error
   [{:keys [data hint] :as error}]
   (let [hint (or hint (:hint data) (:message data))
-        info (with-out-str (fpp/pprint (dissoc data :explain)))
+        info (pp/pprint-str (dissoc data :explain))
         msg  (dm/str "Internal Server Error: " hint)]
 
     (ts/schedule
diff --git a/frontend/src/app/main/repo.cljs b/frontend/src/app/main/repo.cljs
index 6ed957f11..2e3ffb9fa 100644
--- a/frontend/src/app/main/repo.cljs
+++ b/frontend/src/app/main/repo.cljs
@@ -31,6 +31,10 @@
     (= 200 status)
     (rx/of body)
 
+    (= 413 status)
+    (rx/throw {:type :validation
+               :code :request-body-too-large})
+
     (and (>= status 400)
          (map? body))
     (rx/throw body)
diff --git a/frontend/src/app/worker.cljs b/frontend/src/app/worker.cljs
index a37bce958..5889a8cd9 100644
--- a/frontend/src/app/worker.cljs
+++ b/frontend/src/app/worker.cljs
@@ -54,9 +54,11 @@
 
           (reply-error [cause]
             (if (map? cause)
-              (post {:error cause})
-              (post {:error {:type :unexpected
-                             :code :unhandled-error-on-worker
+              (post {:error {:type :worker-error
+                             :code (or (:type cause) :wrapped)
+                             :data cause}})
+              (post {:error {:type :worker-error
+                             :code :unhandled-error
                              :hint (ex-message cause)
                              :data (ex-data cause)}})))
 
diff --git a/frontend/src/app/worker/thumbnails.cljs b/frontend/src/app/worker/thumbnails.cljs
index e5e9d77de..66ac64dfb 100644
--- a/frontend/src/app/worker/thumbnails.cljs
+++ b/frontend/src/app/worker/thumbnails.cljs
@@ -16,22 +16,35 @@
    [beicon.core :as rx]
    [rumext.alpha :as mf]))
 
-(defn- not-found?
-  [{:keys [type]}]
-  (= :not-found type))
-
 (defn- handle-response
-  [response]
+  [{:keys [body status] :as response}]
   (cond
     (http/success? response)
     (rx/of (:body response))
 
-    (http/client-error? response)
-    (rx/throw (:body response))
+    (= status 413)
+    (rx/throw {:type :validation
+               :code :request-body-too-large
+               :hint "request body too large"})
+
+    (and (http/client-error? response)
+         (map? body))
+    (rx/throw body)
 
     :else
-    (rx/throw {:type :unexpected
-               :code (:error response)})))
+    (rx/throw {:type :unexpected-error
+               :code :unhandled-http-response
+               :http-status status
+               :http-body body})))
+
+(defn- not-found?
+  [{:keys [type]}]
+  (= :not-found type))
+
+(defn- body-too-large?
+  [{:keys [type code]}]
+  (and (= :validation type)
+       (= :request-body-too-large code)))
 
 (defn- request-data-for-thumbnail
   [file-id revn]
@@ -88,6 +101,7 @@
     (->> (http/send! request)
          (rx/map http/conditional-decode-transit)
          (rx/mapcat handle-response)
+         (rx/catch body-too-large? (constantly nil))
          (rx/map (constantly params)))))
 
 (defmethod impl/handler :thumbnails/generate