BUG: Dataframe mask method does not work properly with pd.StringDtype() (pandas-dev#40941)

Author: DriesSchaumont

doc/source/whatsnew/v1.3.0.rst

@@ -834,7 +834,7 @@ ExtensionArray
 - Bug in :meth:`DataFrame.where` when ``other`` is a :class:`Series` with :class:`ExtensionArray` dtype (:issue:`38729`)
 - Fixed bug where :meth:`Series.idxmax`, :meth:`Series.idxmin` and ``argmax/min`` fail when the underlying data is :class:`ExtensionArray` (:issue:`32749`, :issue:`33719`, :issue:`36566`)
 - Fixed a bug where some properties of subclasses of :class:`PandasExtensionDtype` where improperly cached (:issue:`40329`)
--
+- Bug in :meth:`DataFrame.mask` where masking a :class:`Dataframe` with an :class:`ExtensionArray` dtype raises ``ValueError`` (:issue:`40941`)
 
 Styler
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