diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index b713eca2eee..588692d3d4d 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -3032,9 +3032,12 @@ class ProxyConfig:
             if use_pkce and redis_usage_cache is None:
                 verbose_proxy_logger.warning(
                     "GENERIC_CLIENT_USE_PKCE=true but Redis is not configured for LiteLLM caching. "
-                    "PKCE verifiers will not be shared across instances. "
+                    "PKCE verifiers will not be shared across instances — callbacks may land on a "
+                    "different pod than the login request and fail silently. "
                     "Configure Redis via the 'cache' section in your proxy config, "
-                    "or enable sticky sessions for multi-instance deployments."
+                    "or enable sticky sessions for single-instance deployments. "
+                    "Set PKCE_STRICT_CACHE_MISS=true to fail fast with a 401 on cache misses "
+                    "instead of continuing without a code_verifier."
                 )
             ### STORE MODEL IN DB ### feature flag for `/model/new`
             store_model_in_db = general_settings.get("store_model_in_db", False)
diff --git a/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py b/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
index f19ebaff0ff..f130dfe16bc 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
@@ -3195,7 +3195,9 @@ class TestPKCEFunctionality:
         mock_cache.async_set_cache = AsyncMock()
 
         with patch.dict(os.environ, {"GENERIC_CLIENT_USE_PKCE": "true"}):
-            with patch("litellm.proxy.proxy_server.user_api_key_cache", mock_cache):
+            with patch("litellm.proxy.proxy_server.redis_usage_cache", None), patch(
+                "litellm.proxy.proxy_server.user_api_key_cache", mock_cache
+            ):
                 # Act
                 result = await SSOAuthenticationHandler.get_generic_sso_redirect_response(
                     generic_sso=mock_sso,