diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index d3982f83bb..00593ea64d 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -4,6 +4,7 @@ Yii Framework 2 Change Log
 2.0.8 under development
 -----------------------
 
+- Enh #10451: Check of existence of `$_SERVER` in `\yii\web\Request` before using it (quantum13)
 - Enh #10610: Added `BaseUrl::$urlManager` to be able to set URL manager used for creating URLs (samdark)
 - Enh #10764: `yii\helpers\Html::tag()` and `::beginTag()` return content without any HTML when the `$tag` attribute is `false` or `null` (pana1990)
 
diff --git a/framework/web/Request.php b/framework/web/Request.php
index 18b9a6eee2..2833c2e9c5 100644
--- a/framework/web/Request.php
+++ b/framework/web/Request.php
@@ -42,7 +42,7 @@ use yii\helpers\StringHelper;
  * @property array $eTags The entity tags. This property is read-only.
  * @property HeaderCollection $headers The header collection. This property is read-only.
  * @property string $hostInfo Schema and hostname part (with port number if needed) of the request URL (e.g.
- * `http://www.yiiframework.com`).
+ * `http://www.yiiframework.com`), null in case it can't be obtained from `$_SERVER` and wasn't set.
  * @property boolean $isAjax Whether this is an AJAX (XMLHttpRequest) request. This property is read-only.
  * @property boolean $isDelete Whether this is a DELETE request. This property is read-only.
  * @property boolean $isFlash Whether this is an Adobe Flash or Adobe Flex request. This property is
@@ -69,8 +69,8 @@ use yii\helpers\StringHelper;
  * @property string $scriptFile The entry script file path.
  * @property string $scriptUrl The relative URL of the entry script.
  * @property integer $securePort Port number for secure requests.
- * @property string $serverName Server name. This property is read-only.
- * @property integer $serverPort Server port number. This property is read-only.
+ * @property string $serverName Server name, null if not available. This property is read-only.
+ * @property integer $serverPort Server port number, null if not available. This property is read-only.
  * @property string $url The currently requested relative URL. Note that the URI returned is URL-encoded.
  * @property string $userAgent User agent, null if not present. This property is read-only.
  * @property string $userHost User host name, null if cannot be determined. This property is read-only.
@@ -526,7 +526,8 @@ class Request extends \yii\base\Request
      * The returned URL does not have an ending slash.
      * By default this is determined based on the user request information.
      * You may explicitly specify it by setting the [[setHostInfo()|hostInfo]] property.
-     * @return string schema and hostname part (with port number if needed) of the request URL (e.g. `http://www.yiiframework.com`)
+     * @return string schema and hostname part (with port number if needed) of the request URL (e.g. `http://www.yiiframework.com`),
+     * null if can't be obtained from `$_SERVER` and wasn't set.
      * @see setHostInfo()
      */
     public function getHostInfo()
@@ -536,7 +537,7 @@ class Request extends \yii\base\Request
             $http = $secure ? 'https' : 'http';
             if (isset($_SERVER['HTTP_HOST'])) {
                 $this->_hostInfo = $http . '://' . $_SERVER['HTTP_HOST'];
-            } else {
+            } elseif (isset($_SERVER['SERVER_NAME'])) {
                 $this->_hostInfo = $http . '://' . $_SERVER['SERVER_NAME'];
                 $port = $secure ? $this->getSecurePort() : $this->getPort();
                 if (($port !== 80 && !$secure) || ($port !== 443 && $secure)) {
@@ -601,13 +602,13 @@ class Request extends \yii\base\Request
         if ($this->_scriptUrl === null) {
             $scriptFile = $this->getScriptFile();
             $scriptName = basename($scriptFile);
-            if (basename($_SERVER['SCRIPT_NAME']) === $scriptName) {
+            if (isset($_SERVER['SCRIPT_NAME']) && basename($_SERVER['SCRIPT_NAME']) === $scriptName) {
                 $this->_scriptUrl = $_SERVER['SCRIPT_NAME'];
-            } elseif (basename($_SERVER['PHP_SELF']) === $scriptName) {
+            } elseif (isset($_SERVER['PHP_SELF']) && basename($_SERVER['PHP_SELF']) === $scriptName) {
                 $this->_scriptUrl = $_SERVER['PHP_SELF'];
             } elseif (isset($_SERVER['ORIG_SCRIPT_NAME']) && basename($_SERVER['ORIG_SCRIPT_NAME']) === $scriptName) {
                 $this->_scriptUrl = $_SERVER['ORIG_SCRIPT_NAME'];
-            } elseif (($pos = strpos($_SERVER['PHP_SELF'], '/' . $scriptName)) !== false) {
+            } elseif (isset($_SERVER['PHP_SELF']) && ($pos = strpos($_SERVER['PHP_SELF'], '/' . $scriptName)) !== false) {
                 $this->_scriptUrl = substr($_SERVER['SCRIPT_NAME'], 0, $pos) . '/' . $scriptName;
             } elseif (!empty($_SERVER['DOCUMENT_ROOT']) && strpos($scriptFile, $_SERVER['DOCUMENT_ROOT']) === 0) {
                 $this->_scriptUrl = str_replace('\\', '/', str_replace($_SERVER['DOCUMENT_ROOT'], '', $scriptFile));
@@ -636,10 +637,17 @@ class Request extends \yii\base\Request
      * Returns the entry script file path.
      * The default implementation will simply return `$_SERVER['SCRIPT_FILENAME']`.
      * @return string the entry script file path
+     * @throws InvalidConfigException
      */
     public function getScriptFile()
     {
-        return isset($this->_scriptFile) ? $this->_scriptFile : $_SERVER['SCRIPT_FILENAME'];
+        if (isset($this->_scriptFile)) {
+            return $this->_scriptFile;
+        } elseif (isset($_SERVER['SCRIPT_FILENAME'])) {
+            return $_SERVER['SCRIPT_FILENAME'];
+        } else {
+            throw new InvalidConfigException('Unable to determine the entry script file path.');
+        }
     }
 
     /**
@@ -825,25 +833,25 @@ class Request extends \yii\base\Request
 
     /**
      * Returns the server name.
-     * @return string server name
+     * @return string server name, null if not available
      */
     public function getServerName()
     {
-        return $_SERVER['SERVER_NAME'];
+        return isset($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : null;
     }
 
     /**
      * Returns the server port number.
-     * @return integer server port number
+     * @return integer server port number, null if not available
      */
     public function getServerPort()
     {
-        return (int) $_SERVER['SERVER_PORT'];
+        return isset($_SERVER['SERVER_PORT']) ? (int) $_SERVER['SERVER_PORT'] : null;
     }
 
     /**
-     * Returns the URL referrer, null if not present
-     * @return string URL referrer, null if not present
+     * Returns the URL referrer.
+     * @return string URL referrer, null if not available
      */
     public function getReferrer()
     {
@@ -851,8 +859,8 @@ class Request extends \yii\base\Request
     }
 
     /**
-     * Returns the user agent, null if not present.
-     * @return string user agent, null if not present
+     * Returns the user agent.
+     * @return string user agent, null if not available
      */
     public function getUserAgent()
     {
@@ -861,7 +869,7 @@ class Request extends \yii\base\Request
 
     /**
      * Returns the user IP address.
-     * @return string user IP address. Null is returned if the user IP address cannot be detected.
+     * @return string user IP address, null if not available
      */
     public function getUserIP()
     {
@@ -869,8 +877,8 @@ class Request extends \yii\base\Request
     }
 
     /**
-     * Returns the user host name, null if it cannot be determined.
-     * @return string user host name, null if cannot be determined
+     * Returns the user host name.
+     * @return string user host name, null if not available
      */
     public function getUserHost()
     {
diff --git a/tests/framework/web/RequestTest.php b/tests/framework/web/RequestTest.php
index aa45e137ce..8ee890a711 100644
--- a/tests/framework/web/RequestTest.php
+++ b/tests/framework/web/RequestTest.php
@@ -146,4 +146,59 @@ class RequestTest extends TestCase
         $this->assertEquals(['post/view', ['id' => 21, 'token' => 'secret']], $result);
         $this->assertEquals($_GET, ['id' => 63]);
     }
+
+    public function testGetHostInfo()
+    {
+        $request = new Request();
+
+        unset($_SERVER['SERVER_NAME'], $_SERVER['HTTP_HOST']);
+        $this->assertEquals(null, $request->getHostInfo());
+
+        $request->setHostInfo('http://servername.com:80');
+        $this->assertEquals('http://servername.com:80', $request->getHostInfo());
+    }
+
+    /**
+     * @expectedException \yii\base\InvalidConfigException
+     */
+    public function testGetScriptFileWithEmptyServer()
+    {
+        $request = new Request();
+        $_SERVER = [];
+
+        $request->getScriptFile();
+    }
+
+    /**
+     * @expectedException \yii\base\InvalidConfigException
+     */
+    public function testGetScriptUrlWithEmptyServer()
+    {
+        $request = new Request();
+        $_SERVER = [];
+
+        $request->getScriptUrl();
+    }
+
+    public function testGetServerName()
+    {
+        $request = new Request();
+
+        $_SERVER['SERVER_NAME'] = 'servername';
+        $this->assertEquals('servername', $request->getServerName());
+
+        unset($_SERVER['SERVER_NAME']);
+        $this->assertEquals(null, $request->getServerName());
+    }
+
+    public function testGetServerPort()
+    {
+        $request = new Request();
+
+        $_SERVER['SERVER_PORT'] = 33;
+        $this->assertEquals(33, $request->getServerPort());
+
+        unset($_SERVER['SERVER_PORT']);
+        $this->assertEquals(null, $request->getServerPort());
+    }
 }