Raise

Author: phofl

pandas/core/generic.py

@@ -95,11 +95,9 @@
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
     AbstractMethodError,
-    ChainedAssignmentError,
     InvalidIndexError,
     SettingWithCopyError,
     SettingWithCopyWarning,
-    _chained_assignment_method_msg,
 )
 from pandas.util._decorators import doc
 from pandas.util._exceptions import find_stack_level
@@ -7089,12 +7087,13 @@ def fillna(
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
             if not PYPY and using_copy_on_write():
-                if sys.getrefcount(self) <= 3:
-                    warnings.warn(
-                        _chained_assignment_method_msg,
-                        ChainedAssignmentError,
-                        stacklevel=2,
-                    )
+                raise ValueError(sys.getrefcount(self))
+                # if sys.getrefcount(self) <= 3:
+                #     warnings.warn(
+                #         _chained_assignment_method_msg,
+                #         ChainedAssignmentError,
+                #         stacklevel=2,
+                #     )
 
         value, method = validate_fillna_kwargs(value, method)
         if method is not None: