Explicitly disable pickling CachedSession objects

1 files changed, 6 insertions, 0 deletions

diff --git a/requests_cache/session.py b/requests_cache/session.py
index e58cc57..3dbdb05 100644
--- a/requests_cache/session.py
+++ b/requests_cache/session.py
@@ -311,6 +311,12 @@ class CacheMixin(MIXIN_BASE):
         """**Deprecated:** Use ``session.cache.remove(expired=True)`` instead"""
         self.cache.delete(expired=True, invalid=True)
 
+    def __getstate__(self):
+        # Unlike requests.Session, CachedSession may contain backend connection objects that can't
+        # be pickled. Support for this could be added if necessary, but for now it's explicitly
+        # disabled to avoid confusing errors upon unpickling.
+        raise NotImplementedError('CachedSession cannot be pickled')
+
     def __repr__(self):
         return f'<CachedSession(cache={repr(self.cache)}, settings={self.settings})>'