diff --git a/app/routers.py b/app/routers.py
index a84c91a..af62fde 100644
--- a/app/routers.py
+++ b/app/routers.py
@@ -657,8 +657,9 @@ async def stop_cycle(unit_id: str, payload: StopCyclePayload = None, db: Session
         return {"status": "ok", "unit_id": unit_id, **result}
 
     except Exception as e:
-        logger.error(f"Stop cycle failed for {unit_id}: {e}")
-        raise HTTPException(status_code=502, detail=str(e))
+        error_msg = str(e) if str(e) else f"{type(e).__name__}: No details available"
+        logger.error(f"Stop cycle failed for {unit_id}: {error_msg}")
+        raise HTTPException(status_code=502, detail=error_msg)
 
 
 @router.post("/{unit_id}/store")
diff --git a/app/services.py b/app/services.py
index e4268f4..f7dbc72 100644
--- a/app/services.py
+++ b/app/services.py
@@ -1381,8 +1381,13 @@ class NL43Client:
         result["stopped"] = True
         logger.info(f"[STOP-CYCLE] Measurement stopped")
 
-        # Step 2: Enable FTP
-        logger.info(f"[STOP-CYCLE] Step 2: Enabling FTP")
+        # Step 2: Reset FTP (disable then enable) to clear any stale state
+        logger.info(f"[STOP-CYCLE] Step 2: Resetting FTP (disable then enable)")
+        try:
+            await self.disable_ftp()
+            logger.info(f"[STOP-CYCLE] FTP disabled")
+        except Exception as e:
+            logger.warning(f"[STOP-CYCLE] FTP disable failed (may already be off): {e}")
         await self.enable_ftp()
         result["ftp_enabled"] = True
         logger.info(f"[STOP-CYCLE] FTP enabled")