diff --git a/app/code/Magento/Eav/Model/TypeLocator/SimpleType.php b/app/code/Magento/Eav/Model/TypeLocator/SimpleType.php
index 73b0516117df6..efc92c432328b 100644
--- a/app/code/Magento/Eav/Model/TypeLocator/SimpleType.php
+++ b/app/code/Magento/Eav/Model/TypeLocator/SimpleType.php
@@ -31,6 +31,7 @@ class SimpleType implements CustomAttributeTypeLocatorInterface
      * Initialize dependencies.
      *
      * @param AttributeRepositoryInterface $attributeRepository
+     * @param ServiceTypeListInterface $serviceTypeList
      */
     public function __construct(
         AttributeRepositoryInterface $attributeRepository,
@@ -41,7 +42,7 @@ public function __construct(
     }
 
     /**
-     * {@inheritdoc}
+     * @inheritdoc
      */
     public function getType($attributeCode, $entityType)
     {
@@ -50,6 +51,11 @@ public function getType($attributeCode, $entityType)
         } catch (NoSuchEntityException $exception) {
             return TypeProcessor::NORMALIZED_ANY_TYPE;
         }
+
+        if ($attribute->getFrontendInput() === 'multiselect') {
+            return TypeProcessor::NORMALIZED_ANY_TYPE;
+        }
+
         $backendType = $attribute->getBackendType();
         $backendTypeMap = [
             'static' => TypeProcessor::NORMALIZED_ANY_TYPE,
@@ -64,7 +70,7 @@ public function getType($attributeCode, $entityType)
     }
 
     /**
-     * {@inheritDoc}
+     * @inheritDoc
      */
     public function getAllServiceDataInterfaces()
     {
diff --git a/app/code/Magento/Eav/Test/Unit/Model/TypeLocator/SimpleTypeTest.php b/app/code/Magento/Eav/Test/Unit/Model/TypeLocator/SimpleTypeTest.php
new file mode 100644
index 0000000000000..0dbec5f741874
--- /dev/null
+++ b/app/code/Magento/Eav/Test/Unit/Model/TypeLocator/SimpleTypeTest.php
@@ -0,0 +1,155 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Eav\Test\Unit\Model\TypeLocator;
+
+use Magento\Eav\Model\TypeLocator\SimpleType;
+use Magento\Eav\Model\AttributeRepository;
+use Magento\Framework\Webapi\CustomAttribute\ServiceTypeListInterface;
+use Magento\Catalog\Model\ResourceModel\Eav\Attribute;
+use Magento\Framework\Reflection\TypeProcessor;
+use Magento\Framework\Exception\NoSuchEntityException;
+
+/**
+ * Class SimpleTypeTest
+ *
+ * @package Magento\Eav\Test\Unit\Model\TypeLocator
+ */
+class SimpleTypeTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * Test testGetType method
+     * @return void
+     */
+    public function testGetTypeWithNonexistentAttribute()
+    {
+        $getException = new NoSuchEntityException();
+        $expected = TypeProcessor::NORMALIZED_ANY_TYPE;
+
+        /** @var AttributeRepository|\PHPUnit_Framework_MockObject_MockObject $attributeRepositoryMock */
+        $attributeRepositoryMock = $this->createMock(AttributeRepository::class);
+        $attributeRepositoryMock->expects($this->any())
+                                ->method('get')
+                                ->willThrowException($getException);
+
+        /** @var ServiceTypeListInterface|\PHPUnit_Framework_MockObject_MockObject $serviceTypeListMock */
+        $serviceTypeListMock = $this->createMock(ServiceTypeListInterface::class);
+
+        /** @var SimpleType|\PHPUnit_Framework_MockObject_MockObject $simpleType */
+        $simpleType = new SimpleType(
+            $attributeRepositoryMock,
+            $serviceTypeListMock
+        );
+
+        $this->assertSame($expected, $simpleType->getType('testAttributeCode', 'testEntityType'));
+    }
+
+    /**
+     * Test testGetType method
+     * @return void
+     */
+    public function testGetTypeWithMultiselectFrontendInput()
+    {
+        $getFrontendInputReturn = 'multiselect';
+        $expected = TypeProcessor::NORMALIZED_ANY_TYPE;
+
+        /** @var Attribute|\PHPUnit_Framework_MockObject_MockObject $attributeMock */
+        $attributeMock = $this->createMock(Attribute::class);
+        $attributeMock->expects($this->any())
+                      ->method('getFrontendInput')
+                      ->willReturn($getFrontendInputReturn);
+
+        /** @var AttributeRepository|\PHPUnit_Framework_MockObject_MockObject $attributeRepositoryMock */
+        $attributeRepositoryMock = $this->createMock(AttributeRepository::class);
+        $attributeRepositoryMock->expects($this->any())
+                                ->method('get')
+                                ->willReturn($attributeMock);
+
+        /** @var ServiceTypeListInterface|\PHPUnit_Framework_MockObject_MockObject $serviceTypeListMock */
+        $serviceTypeListMock = $this->createMock(ServiceTypeListInterface::class);
+
+        /** @var SimpleType|\PHPUnit_Framework_MockObject_MockObject $simpleType */
+        $simpleType = new SimpleType(
+            $attributeRepositoryMock,
+            $serviceTypeListMock
+        );
+
+        $this->assertSame($expected, $simpleType->getType('testAttributeCode', 'testEntityType'));
+    }
+
+    /**
+     * Test testGetType method
+     * @return void
+     */
+    public function testGetTypeWithBackendTypeInMap()
+    {
+        $getFrontendInputReturn = 'textarea';
+        $getBackendTypeReturn = 'text';
+        $expected = TypeProcessor::NORMALIZED_STRING_TYPE;
+
+        /** @var Attribute|\PHPUnit_Framework_MockObject_MockObject $attributeMock */
+        $attributeMock = $this->createMock(Attribute::class);
+        $attributeMock->expects($this->any())
+                      ->method('getFrontendInput')
+                      ->willReturn($getFrontendInputReturn);
+        $attributeMock->expects($this->any())
+                      ->method('getBackendType')
+                      ->willReturn($getBackendTypeReturn);
+
+        /** @var AttributeRepository|\PHPUnit_Framework_MockObject_MockObject $attributeRepositoryMock */
+        $attributeRepositoryMock = $this->createMock(AttributeRepository::class);
+        $attributeRepositoryMock->expects($this->any())
+                                ->method('get')
+                                ->willReturn($attributeMock);
+
+        /** @var ServiceTypeListInterface|\PHPUnit_Framework_MockObject_MockObject $serviceTypeListMock */
+        $serviceTypeListMock = $this->createMock(ServiceTypeListInterface::class);
+
+        /** @var SimpleType|\PHPUnit_Framework_MockObject_MockObject $simpleType */
+        $simpleType = new SimpleType(
+            $attributeRepositoryMock,
+            $serviceTypeListMock
+        );
+
+        $this->assertSame($expected, $simpleType->getType('testAttributeCode', 'testEntityType'));
+    }
+
+    /**
+     * Test testGetType method
+     * @return void
+     */
+    public function testGetTypeWithBackendTypeNotInMap()
+    {
+        $getFrontendInputReturn = 'textarea';
+        $getBackendTypeReturn = 'testBackendTypeNotInMap';
+        $expected = TypeProcessor::NORMALIZED_ANY_TYPE;
+
+        /** @var Attribute|\PHPUnit_Framework_MockObject_MockObject $attributeMock */
+        $attributeMock = $this->createMock(Attribute::class);
+        $attributeMock->expects($this->any())
+                      ->method('getFrontendInput')
+                      ->willReturn($getFrontendInputReturn);
+        $attributeMock->expects($this->any())
+                      ->method('getBackendType')
+                      ->willReturn($getBackendTypeReturn);
+
+        /** @var AttributeRepository|\PHPUnit_Framework_MockObject_MockObject $attributeRepositoryMock */
+        $attributeRepositoryMock = $this->createMock(AttributeRepository::class);
+        $attributeRepositoryMock->expects($this->any())
+                                ->method('get')
+                                ->willReturn($attributeMock);
+
+        /** @var ServiceTypeListInterface|\PHPUnit_Framework_MockObject_MockObject $serviceTypeListMock */
+        $serviceTypeListMock = $this->createMock(ServiceTypeListInterface::class);
+
+        /** @var SimpleType|\PHPUnit_Framework_MockObject_MockObject $simpleType */
+        $simpleType = new SimpleType(
+            $attributeRepositoryMock,
+            $serviceTypeListMock
+        );
+
+        $this->assertSame($expected, $simpleType->getType('testAttributeCode', 'testEntityType'));
+    }
+}
diff --git a/dev/tests/api-functional/testsuite/Magento/Catalog/Api/ProductRepositoryInterfaceTest.php b/dev/tests/api-functional/testsuite/Magento/Catalog/Api/ProductRepositoryInterfaceTest.php
index 1017fb6716709..98668ae7d3fff 100644
--- a/dev/tests/api-functional/testsuite/Magento/Catalog/Api/ProductRepositoryInterfaceTest.php
+++ b/dev/tests/api-functional/testsuite/Magento/Catalog/Api/ProductRepositoryInterfaceTest.php
@@ -663,6 +663,7 @@ public function testProductOptions()
     public function testProductWithMediaGallery()
     {
         $testImagePath = __DIR__ . DIRECTORY_SEPARATOR . '_files' . DIRECTORY_SEPARATOR . 'test_image.jpg';
+        // phpcs:ignore Magento2.Functions.DiscouragedFunction
         $encodedImage = base64_encode(file_get_contents($testImagePath));
         //create a product with media gallery
         $filename1 = 'tiny1' . time() . '.jpg';
@@ -787,7 +788,9 @@ public function testUpdateWithExtensionAttributes(): void
     protected function updateProduct($product)
     {
         if (isset($product['custom_attributes'])) {
-            for ($i=0; $i<sizeof($product['custom_attributes']); $i++) {
+            // phpcs:ignore Magento2.Functions.DiscouragedFunction
+            $size = sizeof($product['custom_attributes']);
+            for ($i=0; $i < $size; $i++) {
                 if ($product['custom_attributes'][$i]['attribute_code'] == 'category_ids'
                     && !is_array($product['custom_attributes'][$i]['value'])
                 ) {
@@ -1208,7 +1211,9 @@ protected function getSimpleProductData($productData = [])
     protected function saveProduct($product, $storeCode = null)
     {
         if (isset($product['custom_attributes'])) {
-            for ($i=0; $i<sizeof($product['custom_attributes']); $i++) {
+            // phpcs:ignore Magento2.Functions.DiscouragedFunction
+            $size = sizeof($product['custom_attributes']);
+            for ($i=0; $i< $size; $i++) {
                 if ($product['custom_attributes'][$i]['attribute_code'] == 'category_ids'
                     && !is_array($product['custom_attributes'][$i]['value'])
                 ) {
@@ -1561,40 +1566,94 @@ public function testUpdateStatus()
      * Test saving product with custom attribute of multiselect type
      *
      * 1. Create multi-select attribute
-     * 2. Create product and set 2 options out of 3 to multi-select attribute
-     * 3. Verify that 2 options are selected
-     * 4. Unselect all options
-     * 5. Verify that non options are selected
+     * 2. Create product
+     * 3. Set 2 options out of 3 to multi-select attribute in string format
+     * 4. Verify that 2 options are selected
      *
      * @magentoApiDataFixture Magento/Catalog/_files/multiselect_attribute.php
      */
-    public function testUpdateMultiselectAttributes()
+    public function testUpdateMultiselectAttributesWithStringValue()
     {
         $multiselectAttributeCode = 'multiselect_attribute';
         $multiselectOptions = $this->getAttributeOptions($multiselectAttributeCode);
-        $option1 = $multiselectOptions[1]['value'];
-        $option2 = $multiselectOptions[2]['value'];
+        $option1Value = $multiselectOptions[1]['value'];
+        $option2Value = $multiselectOptions[2]['value'];
 
         $productData = $this->getSimpleProductData();
+
+        $multiselectValue = "{$option1Value},{$option2Value}";
+        $productData['custom_attributes'] = [
+            ['attribute_code' => $multiselectAttributeCode, 'value' => $multiselectValue]
+        ];
+        $this->saveProduct($productData, 'all');
+
+        $expectedMultiselectValue = "{$option1Value},{$option2Value}";
+        $this->assertMultiselectValue(
+            $productData[ProductInterface::SKU],
+            $multiselectAttributeCode,
+            $expectedMultiselectValue
+        );
+    }
+
+    /**
+     * Test saving product with custom attribute of multiselect type
+     *
+     * 1. Create multi-select attribute
+     * 2. Create product
+     * 3. Set 2 options out of 3 to multi-select attribute in array format
+     * 4. Verify that 2 options are selected
+     *
+     * @magentoApiDataFixture Magento/Catalog/_files/multiselect_attribute.php
+     */
+    public function testUpdateMultiselectAttributesWithArrayValue()
+    {
+        $multiselectAttributeCode = 'multiselect_attribute';
+        $multiselectOptions = $this->getAttributeOptions($multiselectAttributeCode);
+        $option1Value = $multiselectOptions[1]['value'];
+        $option2Value = $multiselectOptions[2]['value'];
+
+        $productData = $this->getSimpleProductData();
+
         $productData['custom_attributes'] = [
-            ['attribute_code' => $multiselectAttributeCode, 'value' => "{$option1},{$option2}"]
+            ['attribute_code' => $multiselectAttributeCode, 'value' => [$option1Value, $option2Value]]
         ];
         $this->saveProduct($productData, 'all');
 
+        $expectedMultiselectValue = "{$option1Value},{$option2Value}";
         $this->assertMultiselectValue(
             $productData[ProductInterface::SKU],
             $multiselectAttributeCode,
-            "{$option1},{$option2}"
+            $expectedMultiselectValue
         );
+    }
 
+    /**
+     * Test saving product with custom attribute of multiselect type
+     *
+     * 1. Create multi-select attribute
+     * 2. Create product
+     * 3. Unselect all options
+     * 4. Verify that non options are selected
+     *
+     * @magentoApiDataFixture Magento/Catalog/_files/multiselect_attribute.php
+     */
+    public function testUpdateMultiselectAttributesWithEmptyValue()
+    {
+        $multiselectAttributeCode = 'multiselect_attribute';
+
+        $productData = $this->getSimpleProductData();
+
+        $multiselectValue = "";
         $productData['custom_attributes'] = [
-            ['attribute_code' => $multiselectAttributeCode, 'value' => ""]
+            ['attribute_code' => $multiselectAttributeCode, 'value' => $multiselectValue]
         ];
         $this->saveProduct($productData, 'all');
+
+        $expectedMultiselectValue = "";
         $this->assertMultiselectValue(
             $productData[ProductInterface::SKU],
             $multiselectAttributeCode,
-            ""
+            $expectedMultiselectValue
         );
     }