diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index 309489672..903fd2b87 100644
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -3697,6 +3697,8 @@ def filter_fn(obj):
                 return list(map(filter_fn, obj))
             elif obj is None or isinstance(obj, (str, int, float, bool)):
                 return obj
+            elif callable(obj):
+                return None
             else:
                 return repr(obj)