Refs #26502 -- Added choices to Form.__getitem__() KeyError message.

1 files changed, 6 insertions, 1 deletions

diff --git a/django/forms/forms.py b/django/forms/forms.py
index df382deda9..ac5cf12425 100644
--- a/django/forms/forms.py
+++ b/django/forms/forms.py
@@ -140,7 +140,12 @@ class BaseForm(object):
             field = self.fields[name]
         except KeyError:
             raise KeyError(
-                "Key %r not found in '%s'" % (name, self.__class__.__name__))
+                "Key '%s' not found in '%s'. Choices are: %s." % (
+                    name,
+                    self.__class__.__name__,
+                    ', '.join(sorted(f for f in self.fields)),
+                )
+            )
         if name not in self._bound_fields_cache:
             self._bound_fields_cache[name] = field.get_bound_field(self, name)
         return self._bound_fields_cache[name]