diff --git a/litellm/proxy/management_endpoints/ui_sso.py b/litellm/proxy/management_endpoints/ui_sso.py
index 3243e4ff084..aceb310646f 100644
--- a/litellm/proxy/management_endpoints/ui_sso.py
+++ b/litellm/proxy/management_endpoints/ui_sso.py
@@ -2685,9 +2685,10 @@ class SSOAuthenticationHandler:
             if client_secret:
                 token_data["client_secret"] = client_secret
 
-        # Tighten the try/except to the POST call only, so httpx connection-pool
-        # teardown in __aexit__ (TLS close, etc.) does not get misclassified as a
-        # token-endpoint failure.
+        # Keep all response processing inside the async with block so that the
+        # response object (which httpx buffers) is always accessed while the client
+        # is still alive.  Network errors on the POST are caught tightly here; TLS
+        # teardown errors from __aexit__ are NOT classified as token failures.
         async with httpx.AsyncClient() as http_client:
             try:
                 response = await http_client.post(token_endpoint, **post_kwargs)
@@ -2703,33 +2704,33 @@ class SSOAuthenticationHandler:
                     code=status.HTTP_401_UNAUTHORIZED,
                 ) from exc
 
-        if response.status_code != 200:
-            verbose_proxy_logger.error(
-                "PKCE token exchange failed. status=%s body=%s",
-                response.status_code,
-                response.text[:500],
-            )
-            raise ProxyException(
-                message=f"Token exchange failed: {response.status_code} - {response.text[:500]}",
-                type=ProxyErrorTypes.auth_error,
-                param="token_exchange",
-                code=status.HTTP_401_UNAUTHORIZED,
-            )
+            if response.status_code != 200:
+                verbose_proxy_logger.error(
+                    "PKCE token exchange failed. status=%s body=%s",
+                    response.status_code,
+                    response.text[:500],
+                )
+                raise ProxyException(
+                    message=f"Token exchange failed: {response.status_code} - {response.text[:500]}",
+                    type=ProxyErrorTypes.auth_error,
+                    param="token_exchange",
+                    code=status.HTTP_401_UNAUTHORIZED,
+                )
 
-        try:
-            token_response: dict = response.json()
-        except Exception as json_err:
-            verbose_proxy_logger.error(
-                "Failed to parse token response as JSON: %s. Body: %s",
-                json_err,
-                response.text[:500],
-            )
-            raise ProxyException(
-                message=f"Token endpoint returned invalid JSON: {json_err}",
-                type=ProxyErrorTypes.auth_error,
-                param="token_exchange",
-                code=status.HTTP_401_UNAUTHORIZED,
-            )
+            try:
+                token_response: dict = response.json()
+            except Exception as json_err:
+                verbose_proxy_logger.error(
+                    "Failed to parse token response as JSON: %s. Body: %s",
+                    json_err,
+                    response.text[:500],
+                )
+                raise ProxyException(
+                    message=f"Token endpoint returned invalid JSON: {json_err}",
+                    type=ProxyErrorTypes.auth_error,
+                    param="token_exchange",
+                    code=status.HTTP_401_UNAUTHORIZED,
+                )
 
         # Some providers return HTTP 200 with an error body (e.g. expired code, replay attack).
         # Also guard against JSON `null` for access_token — it passes key-existence checks
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 6ca9cf85891..171d94bd457 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
@@ -4826,3 +4826,34 @@ async def test_delete_pkce_verifier_swallows_deletion_errors():
         await SSOAuthenticationHandler._delete_pkce_verifier("pkce_verifier:test_state")
 
     failing_cache.async_delete_cache.assert_called_once_with(key="pkce_verifier:test_state")
+
+
+@pytest.mark.asyncio
+async def test_pkce_cache_miss_unexpected_format_raises_proxy_exception():
+    """When cached data exists but has an unrecognized format (not a dict with
+    code_verifier, not a plain string), prepare_token_exchange_parameters raises
+    ProxyException rather than silently falling through to a non-PKCE flow."""
+    import os
+    from unittest.mock import AsyncMock, MagicMock, patch
+
+    from starlette.requests import Request
+
+    from litellm.proxy._types import ProxyException
+    from litellm.proxy.management_endpoints.ui_sso import SSOAuthenticationHandler
+
+    # Cache returns an integer — unexpected format
+    mock_cache = MagicMock()
+    mock_cache.async_get_cache = AsyncMock(return_value=12345)
+
+    mock_request = MagicMock(spec=Request)
+    mock_request.query_params = {"state": "bad_format_state"}
+
+    with pytest.raises(ProxyException) as exc_info:
+        with patch("litellm.proxy.proxy_server.redis_usage_cache", None), patch(
+            "litellm.proxy.proxy_server.user_api_key_cache", mock_cache
+        ), patch.dict(os.environ, {"GENERIC_CLIENT_USE_PKCE": "true"}):
+            await SSOAuthenticationHandler.prepare_token_exchange_parameters(
+                request=mock_request, generic_include_client_id=False
+            )
+
+    assert "cache" in exc_info.value.message.lower() or "verifier" in exc_info.value.message.lower()