diff --git a/backend/bot/services/subscription_service_impl/lifecycle.py b/backend/bot/services/subscription_service_impl/lifecycle.py
index 3f8102e..e4154ad 100644
--- a/backend/bot/services/subscription_service_impl/lifecycle.py
+++ b/backend/bot/services/subscription_service_impl/lifecycle.py
@@ -118,9 +118,21 @@ class SubscriptionLifecycleMixin:
             include_premium=not bool(updated.premium_is_limited),
         )
         panel_payload.update(self._panel_identity_payload_for_user(db_user))
-        await self.panel_service.update_user_details_on_panel(
+        updated_panel = await self.panel_service.update_user_details_on_panel(
             db_user.panel_user_uuid, panel_payload
         )
+        if not updated_panel or updated_panel.get("error"):
+            # The tariff row is already swapped locally; if the panel rejects
+            # the squad/limit update the user sees the new tariff in the app
+            # but stays on the old squads on Remnawave. Surface the failure
+            # so the caller can roll back.
+            logging.warning(
+                "Panel user details update FAILED for tariff switch user %s -> %s. Response: %s",
+                user_id,
+                target.key,
+                updated_panel,
+            )
+            return None
         if converted_bytes:
             await tariff_dal.create_traffic_topup(
                 session,
diff --git a/backend/bot/services/subscription_service_impl/traffic.py b/backend/bot/services/subscription_service_impl/traffic.py
index 13cd3d1..ed5d88e 100644
--- a/backend/bot/services/subscription_service_impl/traffic.py
+++ b/backend/bot/services/subscription_service_impl/traffic.py
@@ -249,9 +249,18 @@ class TrafficMixin:
             include_premium=not bool(getattr(updated_sub, "premium_is_limited", False)),
         )
         panel_payload.update(self._panel_identity_payload_for_user(db_user))
-        await self.panel_service.update_user_details_on_panel(
+        updated_panel = await self.panel_service.update_user_details_on_panel(
             db_user.panel_user_uuid, panel_payload
         )
+        if not updated_panel or updated_panel.get("error"):
+            # Otherwise the user pays for top-up bytes that are recorded locally
+            # but never reach Remnawave — they cannot actually use the traffic.
+            logging.warning(
+                "Panel user details update FAILED for traffic top-up user %s. Response: %s",
+                user_id,
+                updated_panel,
+            )
+            return None
         await tariff_dal.create_traffic_topup(
             session,
             subscription_id=sub.subscription_id,
@@ -347,9 +356,19 @@ class TrafficMixin:
                 include_premium=not premium_is_limited,
             ),
         }
-        await self.panel_service.update_user_details_on_panel(
+        updated_panel = await self.panel_service.update_user_details_on_panel(
             db_user.panel_user_uuid, panel_payload
         )
+        if not updated_panel or updated_panel.get("error"):
+            # Otherwise the user pays for premium top-up but the panel never
+            # re-grants premium squad access (the most common case here is
+            # transitioning from premium_is_limited=True back to False).
+            logging.warning(
+                "Panel user details update FAILED for premium top-up user %s. Response: %s",
+                user_id,
+                updated_panel,
+            )
+            return None
         await tariff_dal.create_traffic_topup(
             session,
             subscription_id=sub.subscription_id,