diff --git a/litellm/proxy/management_endpoints/ui_sso.py b/litellm/proxy/management_endpoints/ui_sso.py
index b1a0b76017b..1d00e721fda 100644
--- a/litellm/proxy/management_endpoints/ui_sso.py
+++ b/litellm/proxy/management_endpoints/ui_sso.py
@@ -2755,11 +2755,12 @@ class SSOAuthenticationHandler:
                 )
 
         if userinfo is None:
+            if userinfo_endpoint:
+                detail = "userinfo endpoint failed and no id_token was present in the token response"
+            else:
+                detail = "no userinfo endpoint is configured (GENERIC_USERINFO_ENDPOINT) and no id_token was present"
             raise ProxyException(
-                message=(
-                    "SSO user info unavailable: userinfo endpoint failed and no id_token "
-                    "was present in the token response."
-                ),
+                message=f"SSO user info unavailable: {detail}.",
                 type=ProxyErrorTypes.auth_error,
                 param="userinfo",
                 code=status.HTTP_401_UNAUTHORIZED,
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 379abdbfa7e..fa591b89660 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_ui_sso.py
@@ -4669,6 +4669,32 @@ async def test_pkce_userinfo_falls_back_to_id_token():
     assert result["email"] == "jwt@example.com"
 
 
+@pytest.mark.asyncio
+async def test_pkce_userinfo_uses_id_token_when_no_endpoint():
+    """When userinfo_endpoint is None, fall back to id_token directly without HTTP call."""
+    import base64
+    import json as _json
+
+    from litellm.proxy.management_endpoints.ui_sso import SSOAuthenticationHandler
+
+    payload = {"sub": "id_token_user", "email": "id@example.com"}
+    encoded_payload = (
+        base64.urlsafe_b64encode(_json.dumps(payload).encode()).rstrip(b"=").decode()
+    )
+    fake_id_token = f"eyJhbGciOiJSUzI1NiJ9.{encoded_payload}.fakesig"
+
+    # No httpx call should happen when userinfo_endpoint is None
+    result = await SSOAuthenticationHandler._get_pkce_userinfo(
+        access_token="some_token",
+        id_token=fake_id_token,
+        userinfo_endpoint=None,
+        additional_headers={},
+    )
+
+    assert result["sub"] == "id_token_user"
+    assert result["email"] == "id@example.com"
+
+
 @pytest.mark.asyncio
 async def test_pkce_userinfo_raises_when_both_sources_unavailable():
     """When userinfo endpoint fails AND no id_token, raise ProxyException."""