diff --git a/framework/base/Model.php b/framework/base/Model.php
index bbbb0d2cbf..d8fbd5b5df 100644
--- a/framework/base/Model.php
+++ b/framework/base/Model.php
@@ -335,9 +335,9 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
      * Errors found during the validation can be retrieved via [[getErrors()]],
      * [[getFirstErrors()]] and [[getFirstError()]].
      *
-     * @param string[]|string $attributeNames attribute name or list of attribute names that should be validated.
-     * If this parameter is empty, it means any attribute listed in the applicable
-     * validation rules should be validated.
+     * @param string[]|string|null $attributeNames attribute name or list of attribute names
+     * that should be validated. If this parameter is empty, it means any attribute listed in
+     * the applicable validation rules should be validated.
      * @param bool $clearErrors whether to call [[clearErrors()]] before performing validation
      * @return bool whether the validation is successful without any error.
      * @throws InvalidArgumentException if the current scenario is unknown.
@@ -426,7 +426,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
 
     /**
      * Returns the validators applicable to the current [[scenario]].
-     * @param string $attribute the name of the attribute whose applicable validators should be returned.
+     * @param string|null $attribute the name of the attribute whose applicable validators should be returned.
      * If this is null, the validators for ALL attributes in the model will be returned.
      * @return \yii\validators\Validator[] the validators applicable to the current [[scenario]].
      */
@@ -561,10 +561,9 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
 
     /**
      * Returns the errors for all attributes or a single attribute.
-     * @param string $attribute attribute name. Use null to retrieve errors for all attributes.
-     * @property array An array of errors for all attributes. Empty array is returned if no error.
-     * The result is a two-dimensional array. See [[getErrors()]] for detailed description.
+     * @param string|null $attribute attribute name. Use null to retrieve errors for all attributes. 
      * @return array errors for all attributes or the specified attribute. Empty array is returned if no error.
+     * See [[getErrors()]] for detailed description.
      * Note that when returning errors for all attributes, the result is a two-dimensional array, like the following:
      *
      * ```php
@@ -704,7 +703,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
 
     /**
      * Returns attribute values.
-     * @param array $names list of attributes whose value needs to be returned.
+     * @param array|null $names list of attributes whose value needs to be returned.
      * Defaults to null, meaning all attributes listed in [[attributes()]] will be returned.
      * If it is an array, only the attributes in the array will be returned.
      * @param array $except list of attributes whose value should NOT be returned.
@@ -857,7 +856,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
      * Note, that the data being populated is subject to the safety check by [[setAttributes()]].
      *
      * @param array $data the data array to load, typically `$_POST` or `$_GET`.
-     * @param string $formName the form name to use to load the data into the model.
+     * @param string|null $formName the form name to use to load the data into the model, empty string when form not use.
      * If not set, [[formName()]] is used.
      * @return bool whether `load()` found the expected form in `$data`.
      */
@@ -887,7 +886,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
      * @param array $models the models to be populated. Note that all models should have the same class.
      * @param array $data the data array. This is usually `$_POST` or `$_GET`, but can also be any valid array
      * supplied by end user.
-     * @param string $formName the form name to be used for loading the data into the models.
+     * @param string|null $formName the form name to be used for loading the data into the models.
      * If not set, it will use the [[formName()]] value of the first model in `$models`.
      * This parameter is available since version 2.0.1.
      * @return bool whether at least one of the models is successfully populated.
@@ -923,7 +922,7 @@ class Model extends Component implements StaticInstanceInterface, IteratorAggreg
      * This method will validate every model. The models being validated may
      * be of the same or different types.
      * @param array $models the models to be validated
-     * @param array $attributeNames list of attribute names that should be validated.
+     * @param array|null $attributeNames list of attribute names that should be validated.
      * If this parameter is empty, it means any attribute listed in the applicable
      * validation rules should be validated.
      * @return bool whether all models are valid. False will be returned if one