diff --git a/backend/auth.py b/backend/auth.py
index 37a076c..590147a 100644
--- a/backend/auth.py
+++ b/backend/auth.py
@@ -93,7 +93,13 @@ def require_auth_flexible(x_auth_token: Optional[str] = Header(default=None), ss
     Raises:
         HTTPException 401 if not authenticated
     """
+    import logging
+    logger = logging.getLogger("uvicorn.error")
+    logger.error(f"[AUTH_FLEX_DEBUG] header={repr(x_auth_token)}, query={repr(ssetoken)}")
+
     session = get_session(x_auth_token or ssetoken)
+    logger.error(f"[AUTH_FLEX_DEBUG] session={repr(session)}")
+
     if not session:
         raise HTTPException(401, "Nicht eingeloggt")
     return session