.. _type-mixed-cannot-be-marked-as-nullable-since-mixed-already-includes-null:

Type mixed cannot be marked as nullable since mixed already includes null
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.. meta::
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		Type mixed cannot be marked as nullable since mixed already includes null: ``mixed`` is a special type, that represents all the available types, include null.
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	:og:title: Type mixed cannot be marked as nullable since mixed already includes null
	:og:description: ``mixed`` is a special type, that represents all the available types, include null
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Description
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``mixed`` is a special type, that represents all the available types, include null.

Example
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.. code-block:: php

   <?php
   
   function foo(?mixed $i = null) {}
   
   ?>

Solutions
_________

+ Remove the ``?`` type with mixed.
+ Keep the ``?`` type, and replace ``mixed``, with some other type.

Related Error Messages
______________________

+ :ref:`type-mixed-can-only-be-used-as-a-standalone-type`