diff --git a/app.py b/app.py
index 39e0bf5..c5ba2a7 100644
--- a/app.py
+++ b/app.py
@@ -949,7 +949,7 @@ def r_start():
         if copy_state['running']:
             return jsonify(error='Bereits aktiv'), 400
     if _copy_thread is not None and _copy_thread.is_alive():
-        return jsonify(error='Abbruch läuft noch, bitte einen Moment warten'), 400
+        return jsonify(error='Abbruch wird noch abgeschlossen - bitte kurz warten und erneut versuchen.'), 400
     cfg  = load_cfg()
     devs = usb_devices()
     src  = next((d for d in devs if d['usb_port'] == cfg.get('source_port')), None)
@@ -1626,6 +1626,7 @@ body{background:var(--bg);color:var(--txt);font-family:-apple-system,BlinkMacSys
       <button id="btn-cancel" class="btn danger" onclick="cancelCopy()" style="display:none">■&nbsp;Abbrechen</button>
       <button class="btn ghost" onclick="refreshDevices()">->&nbsp;Geräte neu laden</button>
     </div>
+    <div id="copy-hint" class="flash" style="display:none"></div>
   </div>
 </div>
 
@@ -2034,7 +2035,9 @@ async function assignPort(role){
 async function startCopy(){
   _dismissed=false;
   if(_autoDismissTimer){ clearTimeout(_autoDismissTimer); _autoDismissTimer=null; }
-  const r=await api('/copy/start','POST'); if(r.error) alert('Fehler: '+r.error);
+  const r=await api('/copy/start','POST');
+  if(r.error) flash('copy-hint','warn',r.error);
+  else $('copy-hint').style.display='none';
 }
 async function cancelCopy(){ await api('/copy/cancel','POST'); }
 
diff --git a/version.txt b/version.txt
index 450f88e..ace256e 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-1.0.20
\ No newline at end of file
+1.0.21
\ No newline at end of file