diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index ec38cf0cccd..302698ff536 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -9,6 +9,7 @@ Yii Framework 2 Change Log
 - Bug #18469: Fixed `Link::serialize(array $links)` method in `yii\web\Link` (ggh2e3)
 - Bug #19691: Allow using custom class to style error summary (skepticspriggan)
 - Bug #20040: Fix type `boolean` in `MSSQL` (terabytesoftw)
+- Bug #20055: Fix Response header X-Pagination-Total-Count is always 0 (lav45, xicond)
 - Bug #20005: Fix `yii\console\controllers\ServeController` to specify the router script (terabytesoftw)
 - Bug #19060: Fix `yii\widgets\Menu` bug when using Closure for active item and adding additional tests in `tests\framework\widgets\MenuTest` (atrandafir)
 - Bug #13920: Fixed erroneous validation for specific cases (tim-fischer-maschinensucher)
diff --git a/framework/data/ActiveDataProvider.php b/framework/data/ActiveDataProvider.php
index b0aab615305..9280c1c0d1c 100644
--- a/framework/data/ActiveDataProvider.php
+++ b/framework/data/ActiveDataProvider.php
@@ -103,7 +103,6 @@ protected function prepareModels()
         }
         $query = clone $this->query;
         if (($pagination = $this->getPagination()) !== false) {
-            $pagination->totalCount = $this->getTotalCount();
             if ($pagination->totalCount === 0) {
                 return [];
             }
diff --git a/framework/data/ArrayDataProvider.php b/framework/data/ArrayDataProvider.php
index 1655b18b5bb..14511c54556 100644
--- a/framework/data/ArrayDataProvider.php
+++ b/framework/data/ArrayDataProvider.php
@@ -87,14 +87,10 @@ protected function prepareModels()
             $models = $this->sortModels($models, $sort);
         }
 
-        if (($pagination = $this->getPagination()) !== false) {
-            $pagination->totalCount = $this->getTotalCount();
-
-            if ($pagination->getPageSize() > 0) {
-                $models = array_slice($models, $pagination->getOffset(), $pagination->getLimit(), true);
-            }
+        $pagination = $this->getPagination();
+        if ($pagination !== false && $pagination->getPageSize() > 0) {
+            $models = array_slice($models, $pagination->getOffset(), $pagination->getLimit(), true);
         }
-
         return $models;
     }
 
diff --git a/framework/data/BaseDataProvider.php b/framework/data/BaseDataProvider.php
index 623ead89306..409b9f28bca 100644
--- a/framework/data/BaseDataProvider.php
+++ b/framework/data/BaseDataProvider.php
@@ -165,12 +165,12 @@ public function getCount()
      */
     public function getTotalCount()
     {
-        if ($this->getPagination() === false) {
+        if ($this->_pagination === false) {
             return $this->getCount();
-        } elseif ($this->_totalCount === null) {
+        }
+        if ($this->_totalCount === null) {
             $this->_totalCount = $this->prepareTotalCount();
         }
-
         return $this->_totalCount;
     }
 
@@ -194,7 +194,6 @@ public function getPagination()
         if ($this->_pagination === null) {
             $this->setPagination([]);
         }
-
         return $this->_pagination;
     }
 
@@ -218,9 +217,13 @@ public function setPagination($value)
                 $config['pageParam'] = $this->id . '-page';
                 $config['pageSizeParam'] = $this->id . '-per-page';
             }
-            $this->_pagination = Yii::createObject(array_merge($config, $value));
-        } elseif ($value instanceof Pagination || $value === false) {
+            $value = Yii::createObject(array_merge($config, $value));
+        }
+        if ($value instanceof Pagination) {
+            $value->totalCount = $this->getTotalCount();
             $this->_pagination = $value;
+        } elseif ($value === false) {
+            $this->_pagination = false;
         } else {
             throw new InvalidArgumentException('Only Pagination instance, configuration array or false is allowed.');
         }
diff --git a/framework/data/SqlDataProvider.php b/framework/data/SqlDataProvider.php
index 97c6000c053..3ecf0595c9a 100644
--- a/framework/data/SqlDataProvider.php
+++ b/framework/data/SqlDataProvider.php
@@ -128,7 +128,6 @@ protected function prepareModels()
         }
 
         if ($pagination !== false) {
-            $pagination->totalCount = $this->getTotalCount();
             $limit = $pagination->getLimit();
             $offset = $pagination->getOffset();
         }
diff --git a/tests/framework/data/ActiveDataProviderTest.php b/tests/framework/data/ActiveDataProviderTest.php
index af96dfef267..789a0337260 100644
--- a/tests/framework/data/ActiveDataProviderTest.php
+++ b/tests/framework/data/ActiveDataProviderTest.php
@@ -170,9 +170,8 @@ public function testPaginationBeforeModels()
             'query' => $query->from('order')->orderBy('id'),
         ]);
         $pagination = $provider->getPagination();
-        $this->assertEquals(0, $pagination->getPageCount());
-        $this->assertCount(3, $provider->getModels());
         $this->assertEquals(1, $pagination->getPageCount());
+        $this->assertCount(3, $provider->getModels());
 
         $provider->getPagination()->pageSize = 2;
         $this->assertCount(3, $provider->getModels());
diff --git a/tests/framework/rest/SerializerTest.php b/tests/framework/rest/SerializerTest.php
index 91b627b8f8e..f2e0ed72e5e 100644
--- a/tests/framework/rest/SerializerTest.php
+++ b/tests/framework/rest/SerializerTest.php
@@ -439,6 +439,30 @@ public function testHeadSerializeDataProvider($dataProvider, $expectedResult, $s
         ]);
         $serializer->preserveKeys = $saveKeys;
         $this->assertEmpty($serializer->serialize($dataProvider));
+        $this->assertNotEmpty($serializer->response->getHeaders()->get($serializer->totalCountHeader));
+
+        $arrayDataProviderMock = $this->getMockBuilder(ArrayDataProvider::className())
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        // stub getModels to prevent empty
+        $arrayDataProviderMock
+            ->method('getModels')
+            ->willReturn($expectedResult);
+
+        // stub getPagination for header
+        $arrayDataProviderMock
+            ->method('getPagination')
+            ->willReturn($dataProvider->getPagination());
+
+        // assert normal HEAD is empty response
+        $this->assertEmpty($serializer->serialize($arrayDataProviderMock));
+
+        // Test #20002:  Set up the expectation for the getModels method
+        $arrayDataProviderMock->expects($this->never())
+            ->method('getModels');
+
+        // reset Method
         unset($_POST[$request->methodParam], $_SERVER['REQUEST_METHOD']);
     }