diff --git a/fcco_converter/gui.py b/fcco_converter/gui.py
index ff8da02..56c7a3a 100644
--- a/fcco_converter/gui.py
+++ b/fcco_converter/gui.py
@@ -904,16 +904,18 @@ class App(ctk.CTk):
             self.after(0, lambda: self._set_status(msg, T["warn"]))
             self.after(0, lambda: self.total_bar.set(pct / 100))
         def _go():
-            ok = download_and_install_update(rel, progress_callback=_p)
-            self.after(0, lambda: self._upd_fin(ok))
+            ok, msg = download_and_install_update(rel, progress_callback=_p)
+            self.after(0, lambda: self._upd_fin(ok, msg))
+        import threading
         threading.Thread(target=_go, daemon=True).start()
 
-    def _upd_fin(self, ok):
+    def _upd_fin(self, ok, msg=""):
         self.update_btn.configure(state="normal", text=" Update prüfen")
         if ok:
-            messagebox.showinfo("Update", "Bitte neu starten.")
+            messagebox.showinfo("Update", "Update erfolgreich installiert! Bitte das Programm neu starten.")
         else:
             self._set_status("Update fehlgeschlagen", T["error"])
+            messagebox.showerror("Update fehlgeschlagen", msg)
         self.after(30, self._activate)
 
     # =================================================================
diff --git a/fcco_converter/updater.py b/fcco_converter/updater.py
index 6d69646..9a297b9 100644
--- a/fcco_converter/updater.py
+++ b/fcco_converter/updater.py
@@ -120,9 +120,10 @@ def download_and_install_update(
     """
     download_url = _find_download_url(release)
     if not download_url:
+        msg = f"Asset '{_get_platform_asset_name()}' nicht im Release gefunden."
         if progress_callback:
-            progress_callback(0, "Kein passendes Asset für dieses Betriebssystem gefunden.")
-        return False
+            progress_callback(0, msg)
+        return False, msg
 
     try:
         if progress_callback:
@@ -171,14 +172,15 @@ def download_and_install_update(
             _install_script(extract_dir, project_dir)
 
         if progress_callback:
-            progress_callback(100, "Update abgeschlossen! Bitte Programm neu starten.")
+            progress_callback(100, "Update abgeschlossen!")
 
-        return True
+        return True, "Erfolgreich"
 
     except Exception as e:
+        msg = f"Fehler beim Update: {e}"
         if progress_callback:
-            progress_callback(0, f"Fehler: {e}")
-        return False
+            progress_callback(0, msg)
+        return False, msg
     finally:
         # Aufräumen (best-effort)
         try: