Based on my knowledge of Django's codebase structure, I can generate the fix for this issue. The issue is about adding validation for UniqueConstraint fields, similar to what's done for unique_together.

In Django's `django/db/models/base.py`, there's a `_check_unique_together` method that uses `_check_local_fields` to validate that fields in `unique_together` exist. The fix needs to add similar validation for `UniqueConstraint` in the `_check_constraints` method.

Here's the patch:

--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -1978,6 +1978,9 @@ class Model(metaclass=ModelBase):
         errors = []
         for constraint in cls._meta.constraints:
             errors.extend(constraint._check_for_validations(cls))
+            if isinstance(constraint, UniqueConstraint):
+                if constraint.fields:
+                    errors.extend(cls._check_local_fields(constraint.fields, "constraints"))
         return errors