diff --git a/patch_manager_v2.py b/patch_manager_v2.py
index 46a9438..13e7b5b 100644
--- a/patch_manager_v2.py
+++ b/patch_manager_v2.py
@@ -670,15 +670,72 @@ def build_fqdn(server, env):
         return [server, f"{server}.sanef.groupe"]
 
 def load_key(keyfile):
-    if not keyfile or not os.path.exists(keyfile.strip('"').strip("'")):
+    """Charge une clé SSH privée. Retourne l'objet PKey ou None.
+    Si format PuTTY (.ppk), tente conversion auto via puttygen vers OpenSSH PEM.
+    Stocke le détail de l'échec dans load_key.last_error pour affichage UI."""
+    load_key.last_error = None
+    if not keyfile:
         return None
     keyfile = keyfile.strip('"').strip("'")
+    if not os.path.exists(keyfile):
+        load_key.last_error = f"Fichier clé introuvable : {keyfile}"
+        return None
+
+    # Détection format PuTTY (.ppk)
+    try:
+        with open(keyfile, "r", encoding="utf-8", errors="ignore") as f:
+            first_line = f.readline().strip()
+    except Exception as ex:
+        load_key.last_error = f"Lecture impossible : {ex}"
+        return None
+
+    is_ppk = first_line.startswith("PuTTY-User-Key-File-")
+    if is_ppk:
+        # Paramiko ne lit pas .ppk nativement → tenter conversion auto via puttygen
+        converted = keyfile + ".openssh"
+        puttygen_paths = [
+            r"C:\Program Files\PuTTY\puttygen.exe",
+            r"C:\Program Files (x86)\PuTTY\puttygen.exe",
+            "puttygen",  # si dans PATH
+            "puttygen.exe",
+        ]
+        import subprocess
+        converted_ok = False
+        for pg in puttygen_paths:
+            try:
+                subprocess.run(
+                    [pg, keyfile, "-O", "private-openssh", "-o", converted],
+                    check=True, capture_output=True, timeout=10,
+                )
+                converted_ok = True
+                break
+            except (FileNotFoundError, subprocess.SubprocessError, OSError):
+                continue
+        if not converted_ok:
+            load_key.last_error = (
+                f"Format PuTTY (.ppk) détecté pour {os.path.basename(keyfile)}. "
+                f"Paramiko ne lit pas ce format nativement et puttygen.exe est introuvable. "
+                f"Convertir manuellement : "
+                f'puttygen "{keyfile}" -O private-openssh -o "{keyfile}.openssh" '
+                f"puis pointer la conf vers le fichier converti."
+            )
+            return None
+        keyfile = converted
+
+    # Tenter chargement PEM/OpenSSH (multi-format)
+    last_ex = None
     for cls in [paramiko.RSAKey, paramiko.Ed25519Key, paramiko.ECDSAKey]:
         try:
             return cls.from_private_key_file(keyfile)
-        except Exception:
+        except Exception as ex:
+            last_ex = ex
             continue
+    load_key.last_error = (
+        f"Aucun loader paramiko n'a pu lire {os.path.basename(keyfile)} "
+        f"(RSA / Ed25519 / ECDSA tentés). Dernière erreur : {last_ex}"
+    )
     return None
+load_key.last_error = None
 
 def ssh_connect(server, env, settings, pkey, pkey2, cyb_password=None):
     """Connexion SSH avec fallback FQDN et clé. Retourne (client, hostname_effectif)"""
@@ -2294,8 +2351,28 @@ class PatchManagerV2:
             self._reload_keys()
 
     def _reload_keys(self):
-        self.pkey  = load_key(self.settings.get("keyfile",""))
-        self.pkey2 = load_key(self.settings.get("keyfile2",""))
+        errors = []
+        kf1 = self.settings.get("keyfile", "")
+        if kf1:
+            self.pkey = load_key(kf1)
+            if self.pkey is None and load_key.last_error:
+                errors.append(f"Clé 1 ({kf1}) :\n{load_key.last_error}")
+        else:
+            self.pkey = None
+        kf2 = self.settings.get("keyfile2", "")
+        if kf2:
+            self.pkey2 = load_key(kf2)
+            if self.pkey2 is None and load_key.last_error:
+                errors.append(f"Clé 2 ({kf2}) :\n{load_key.last_error}")
+        else:
+            self.pkey2 = None
+        if errors:
+            try:
+                messagebox.showwarning("Clés SSH non chargées", "\n\n".join(errors))
+            except Exception:
+                # Pas de UI dispo (lancement CLI ?), juste print
+                for e in errors:
+                    print(f"[load_key] {e}")
 
     # ==========================================================================
     # ONGLET 1 — LOGIQUE