diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index b369bcf714..3690a31ae9 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -11,6 +11,8 @@ Yii Framework 2 Change Log
 - Bug #17829: `yii\helpers\ArrayHelper::filter` now correctly filters data when passing a filter with more than 2 levels (rhertogh)
 - Enh #7622: Allow `yii\data\ArrayDataProvider` to control the sort flags for `sortModels` through `yii\data\Sort::sortFlags` property (askobara)
 - Bug #17863: `\yii\helpers\BaseInflector::slug()` doesn't work with an empty string as a replacement argument (haruatari)
+- Bug #17875: Revert `move_uploaded_file()` function instead of `copy()` and `unlink()` for saving uploaded files when POST request (sup-ham)
+
 
 2.0.32 January 21, 2020
 -----------------------
diff --git a/framework/web/UploadedFile.php b/framework/web/UploadedFile.php
index 03f0a668c7..7a97b30c7b 100644
--- a/framework/web/UploadedFile.php
+++ b/framework/web/UploadedFile.php
@@ -178,10 +178,14 @@ class UploadedFile extends BaseObject
         if ($this->hasError) {
             return false;
         }
-        if (false === $this->copyTempFile(Yii::getAlias($file))) {
-            return false;
+
+        $targetFile = Yii::getAlias($file);
+        if (is_resource($this->_tempResource)) {
+            $result = $this->copyTempFile($targetFile);
+            return $deleteTempFile ? @fclose($this->_tempResource) : (bool) $result;
         }
-        return !$deleteTempFile || $this->deleteTempFile();
+
+        return $deleteTempFile ? move_uploaded_file($this->tempName, $targetFile) : copy($this->tempName, $targetFile);
     }
 
     /**
@@ -193,9 +197,6 @@ class UploadedFile extends BaseObject
      */
     protected function copyTempFile($targetFile)
     {
-        if (!is_resource($this->_tempResource)) {
-            return $this->isUploadedFile($this->tempName) && copy($this->tempName, $targetFile);
-        }
         $target = fopen($targetFile, 'wb');
         if ($target === false) {
             return false;
@@ -207,32 +208,6 @@ class UploadedFile extends BaseObject
         return $result;
     }
 
-    /**
-     * Delete temporary file
-     *
-     * @return bool if file was deleted
-     * @since 2.0.32
-     */
-    protected function deleteTempFile()
-    {
-        if (is_resource($this->_tempResource)) {
-            return @fclose($this->_tempResource);
-        }
-        return $this->isUploadedFile($this->tempName) && @unlink($this->tempName);
-    }
-
-    /**
-     * Check if file is uploaded file
-     *
-     * @param string $file path to the file to check
-     * @return bool
-     * @since 2.0.32
-     */
-    protected function isUploadedFile($file)
-    {
-        return is_uploaded_file($file);
-    }
-
     /**
      * @return string original file base name
      */
diff --git a/tests/framework/web/UploadedFileTest.php b/tests/framework/web/UploadedFileTest.php
index 6fe85ca37e..4702c5adb6 100644
--- a/tests/framework/web/UploadedFileTest.php
+++ b/tests/framework/web/UploadedFileTest.php
@@ -89,12 +89,11 @@ class UploadedFileTest extends TestCase
 
     public function testSaveAs()
     {
-        $tmpImage = UploadedFileMock::getInstance(new ModelStub(), 'temp_image');
+        $tmpImage = UploadedFile::getInstance(new ModelStub(), 'temp_image');
         $targetFile = '@runtime/test_saved_uploaded_file_' . time();
 
         $this->assertEquals(true, $tmpImage->saveAs($targetFile, $deleteTempFile = false));
-        $this->assertEquals(true, $tmpImage->saveAs($targetFile, $deleteTempFile = true));
-        $this->assertEquals(false, $tmpImage->saveAs($targetFile)); // temp file should not exist
+        $this->markTestIncomplete("`$deleteTempFile` flag simply uses php's move_uploaded_file() method, so this not work in test");
 
         @unlink($targetFile);
     }
@@ -110,7 +109,11 @@ class UploadedFileTest extends TestCase
         $_FILES['ModelStub'] = $_FILES['Item']; // $_FILES[Item] here from testParse() above
         $tmpFile = UploadedFile::getInstance($model, 'file');
 
-        $this->assertEquals(true, $tmpFile->saveAs($targetFile));
+        $this->assertEquals($tmpFile->saveAs($targetFile, $deleteTempFile = false), true);
+        $this->assertEquals($tmpFile->saveAs($targetFile), true);
+
+        $this->assertEquals($tmpFile->saveAs($targetFile), false); // has deleted before
+
         @unlink($targetFile);
     }
 }
diff --git a/tests/framework/web/mocks/UploadedFileMock.php b/tests/framework/web/mocks/UploadedFileMock.php
deleted file mode 100644
index 9bebceee9d..0000000000
--- a/tests/framework/web/mocks/UploadedFileMock.php
+++ /dev/null
@@ -1,19 +0,0 @@
-<?php
-/**
- * @link http://www.yiiframework.com/
- * @copyright Copyright (c) 2008 Yii Software LLC
- * @license http://www.yiiframework.com/license/
- */
-
-namespace yiiunit\framework\web\mocks;
-
-class UploadedFileMock extends \yii\web\UploadedFile
-{
-    /**
-     * @inheritDoc
-     */
-    protected function isUploadedFile($file)
-    {
-        return is_file($file); // is_uploaded_file() won't work in test
-    }
-}