diff --git a/yesod-core/src/Yesod/Core/Internal/Run.hs b/yesod-core/src/Yesod/Core/Internal/Run.hs
index 759fa2bc..eca2c8b6 100644
--- a/yesod-core/src/Yesod/Core/Internal/Run.hs
+++ b/yesod-core/src/Yesod/Core/Internal/Run.hs
@@ -40,6 +40,8 @@ import           Yesod.Routes.Class           (Route, renderRoute)
 import           Control.DeepSeq              (($!!), NFData)
 import           UnliftIO.Exception
 
+import Debug.Trace (traceStack)
+
 -- | Convert a synchronous exception into an ErrorResponse
 toErrorHandler :: SomeException -> IO ErrorResponse
 toErrorHandler e0 = handleAny errFromShow $