diff --git a/classes/context/Context.class.php b/classes/context/Context.class.php
index ef96466d0..06d766fec 100644
--- a/classes/context/Context.class.php
+++ b/classes/context/Context.class.php
@@ -719,9 +719,10 @@ class Context
 	 * Append string to browser title
 	 *
 	 * @param string $title Browser title to be appended
+	 * @param string $delimiter
 	 * @return void
 	 */
-	public static function addBrowserTitle($title)
+	public static function addBrowserTitle($title, $delimiter = ' - ')
 	{
 		if(!$title)
 		{
@@ -729,7 +730,7 @@ class Context
 		}
 		if(self::$_instance->browser_title)
 		{
-			self::$_instance->browser_title .= ' - ' . $title;
+			self::$_instance->browser_title .= $delimiter . $title;
 		}
 		else
 		{
@@ -741,9 +742,10 @@ class Context
 	 * Prepend string to browser title
 	 *
 	 * @param string $title Browser title to be prepended
+	 * @param string $delimiter
 	 * @return void
 	 */
-	public static function prependBrowserTitle($title)
+	public static function prependBrowserTitle($title, $delimiter = ' - ')
 	{
 		if(!$title)
 		{
@@ -751,7 +753,7 @@ class Context
 		}
 		if(self::$_instance->browser_title)
 		{
-			self::$_instance->browser_title = $title . ' - ' . self::$_instance->browser_title;
+			self::$_instance->browser_title = $title . $delimiter . self::$_instance->browser_title;
 		}
 		else
 		{
@@ -903,7 +905,7 @@ class Context
 	 * Return string accoring to the inputed code
 	 *
 	 * @param string $code Language variable name
-	 * @return string If string for the code exists returns it, otherwise returns original code
+	 * @return mixed
 	 */
 	public static function getLang($code)
 	{
@@ -1020,7 +1022,7 @@ class Context
 	 * @param string $key
 	 * @param mixed $charset charset
 	 * @see arrayConvWalkCallback will replaced array_walk_recursive in >=PHP5
-	 * @return void
+	 * @return ?bool
 	 */
 	public static function checkConvertFlag(&$val, $key = null, $charset = null)
 	{
@@ -1049,7 +1051,7 @@ class Context
 	 * @param string $key
 	 * @param string $charset character set
 	 * @see arrayConvWalkCallback will replaced array_walk_recursive in >=PHP5
-	 * @return object converted object
+	 * @return void
 	 */
 	public static function doConvertEncoding(&$val, $key = null, $charset = 'CP949')
 	{
@@ -1315,7 +1317,7 @@ class Context
 	 *
 	 * @return void
 	 */
-	private static function setUploadInfo()
+	public static function setUploadInfo()
 	{
 		if (!isset($_SERVER['REQUEST_METHOD']) || $_SERVER['REQUEST_METHOD'] !== 'POST' || !$_FILES)
 		{
@@ -1617,10 +1619,12 @@ class Context
 	}
 
 	/**
-	 * Display a generic error page and exit.
+	 * Display a generic error page.
 	 *
 	 * @param string $title
 	 * @param string $message
+	 * @param int $status
+	 * @param string $location
 	 * @return void
 	 */
 	public static function displayErrorPage($title = 'Error', $message = '', $status = 500, $location = '')
@@ -1963,7 +1967,7 @@ class Context
 	 *
 	 * @param string $key Key
 	 * @param mixed $val Value
-	 * @param mixed $replace_request_arg
+	 * @param bool $replace_request_arg
 	 * @return void
 	 */
 	public static function set($key, $val, $replace_request_arg = false)
@@ -2020,17 +2024,20 @@ class Context
 	/**
 	 * Get one more vars in object vars with given arguments(key1, key2, key3,...)
 	 *
-	 * @return object
+	 * @return ?object
 	 */
 	public static function gets()
 	{
-		$num_args = func_num_args();
-		if($num_args < 1)
+		$args_list = func_get_args();
+		if (count($args_list) < 1)
 		{
 			return;
 		}
+		if (count($args_list) === 1 && is_array($args_list[0]))
+		{
+			$args_list = $args_list[0];
+		}
 
-		$args_list = func_get_args();
 		$output = new stdClass;
 		self::$_user_vars = self::$_user_vars !== null ? self::$_user_vars : new stdClass;
 		foreach($args_list as $key)
@@ -3003,7 +3010,7 @@ class Context
 	 * Add OpenGraph metadata
 	 *
 	 * @param string $name
-	 * @param mixed $content
+	 * @param array $content
 	 * @return void
 	 */
 	public static function addOpenGraphData($name, $content)
@@ -3040,6 +3047,6 @@ class Context
 	 */
 	public static function getCanonicalURL()
 	{
-		return self::$_instance->canonical_url;
+		return self::$_instance->canonical_url ?? '';
 	}
 }
diff --git a/classes/frontendfile/FrontEndFileHandler.class.php b/classes/frontendfile/FrontEndFileHandler.class.php
index f98958256..a530ee3ce 100644
--- a/classes/frontendfile/FrontEndFileHandler.class.php
+++ b/classes/frontendfile/FrontEndFileHandler.class.php
@@ -205,13 +205,13 @@ class FrontEndFileHandler extends Handler
 	 * Get file information
 	 *
 	 * @param string $fileName The file name
-	 * @param string $targetIe Target IE of file
+	 * @param string $unused Formerly targetIe
 	 * @param string $media Media of file
 	 * @param array $vars Variables for LESS and SCSS
 	 * @param bool $forceMinify Whether this file should be minified
 	 * @return stdClass The file information
 	 */
-	protected function getFileInfo($fileName, $targetIe = '', $media = 'all', $vars = array(), $isCommon = false)
+	protected function getFileInfo($fileName, $unused = '', $media = 'all', $vars = array(), $isCommon = false)
 	{
 		$pathInfo = pathinfo($fileName);
 
@@ -423,13 +423,13 @@ class FrontEndFileHandler extends Handler
 	 * Unload front end file
 	 *
 	 * @param string $fileName The file name to unload
-	 * @param string $targetIe Target IE of file to unload
+	 * @param string $unused Formerly targetIe
 	 * @param string $media Media of file to unload. Only use when file is css.
 	 * @return void
 	 */
-	public function unloadFile($fileName, $targetIe = '', $media = 'all')
+	public function unloadFile($fileName, $unused = '', $media = 'all')
 	{
-		$file = $this->getFileInfo($fileName, $targetIe, $media);
+		$file = $this->getFileInfo($fileName, $unused, $media);
 
 		if($file->fileExtension == 'css')
 		{
diff --git a/classes/module/ModuleHandler.class.php b/classes/module/ModuleHandler.class.php
index 0a00ad038..b23d108f5 100644
--- a/classes/module/ModuleHandler.class.php
+++ b/classes/module/ModuleHandler.class.php
@@ -49,7 +49,7 @@ class ModuleHandler extends Handler
 	 * prepares variables to use in moduleHandler
 	 * @param string $module name of module
 	 * @param string $act name of action
-	 * @param int $mid
+	 * @param string $mid
 	 * @param int $document_srl
 	 * @param int $module_srl
 	 * @return void
diff --git a/classes/module/ModuleObject.class.php b/classes/module/ModuleObject.class.php
index f77996e99..a736136f4 100644
--- a/classes/module/ModuleObject.class.php
+++ b/classes/module/ModuleObject.class.php
@@ -128,7 +128,7 @@ class ModuleObject extends BaseObject
 	 * setter to set an url for redirection
 	 *
 	 * @param string|array $url url for redirection
-	 * @return $this
+	 * @return object
 	 */
 	public function setRedirectUrl($url = './', $output = NULL)
 	{
@@ -151,7 +151,7 @@ class ModuleObject extends BaseObject
 	/**
 	 * get url for redirection
 	 *
-	 * @return string
+	 * @return ?string
 	 */
 	public function getRedirectUrl()
 	{
@@ -546,7 +546,7 @@ class ModuleObject extends BaseObject
 	/**
 	 * retrieve the directory path of the template directory
 	 *
-	 * @return string
+	 * @return ?string
 	 */
 	public function getTemplateFile()
 	{
@@ -577,7 +577,7 @@ class ModuleObject extends BaseObject
 	/**
 	 * retrieve the directory path of the template directory
 	 *
-	 * @return string
+	 * @return ?string
 	 */
 	public function getTemplatePath()
 	{
@@ -600,7 +600,7 @@ class ModuleObject extends BaseObject
 	/**
 	 * retreived the file name of edited_layout_file
 	 *
-	 * @return string
+	 * @return ?string
 	 */
 	public function getEditedLayoutFile()
 	{
@@ -622,7 +622,7 @@ class ModuleObject extends BaseObject
 	/**
 	 * get the file name of the layout file
 	 *
-	 * @return string
+	 * @return ?string
 	 */
 	public function getLayoutFile()
 	{
@@ -653,9 +653,9 @@ class ModuleObject extends BaseObject
 	/**
 	 * set the directory path of the layout directory
 	 *
-	 * @return string
+	 * @return ?string
 	 */
-	public function getLayoutPath($layout_name = "", $layout_type = "P")
+	public function getLayoutPath()
 	{
 		return $this->layout_path;
 	}
diff --git a/common/functions.php b/common/functions.php
index 7ddb59b59..72b3e9e5b 100644
--- a/common/functions.php
+++ b/common/functions.php
@@ -11,7 +11,7 @@
  *
  * @param string $key
  * @param string $value (optional)
- * @return mixed
+ * @return string|array|null
  */
 function config(string $key, $value = null)
 {
@@ -256,7 +256,7 @@ function escape_dqstr(string $str): string
  * @param string $escape_char The escape character (default: backslash)
  * @return array
  */
-function explode_with_escape(string $delimiter, string $str, $limit = 0, $escape_char = '\\'): array
+function explode_with_escape(string $delimiter, string $str, int $limit = 0, string $escape_char = '\\'): array
 {
 	if ($limit < 1) $limit = 0;
 	$str = (string)$str;
@@ -417,7 +417,7 @@ function base64_decode_urlsafe(string $str): string
 /**
  * This function shortens a number using common suffixes.
  *
- * @param int $number The number to shorten
+ * @param int|float $number The number to shorten
  * @param int $significant_digits The number of significant digits to retain
  * @return string
  */
diff --git a/common/js/common.js b/common/js/common.js
index e4c9602f4..4c30996d7 100644
--- a/common/js/common.js
+++ b/common/js/common.js
@@ -279,6 +279,7 @@ Rhymix.redirectToUrl = function(url) {
  * @param string url
  * @param string target
  * @param string features
+ * @return void
  */
 Rhymix.openWindow = function(url, target, features) {
 
diff --git a/common/legacy.php b/common/legacy.php
index f236ae67b..d1499de9d 100644
--- a/common/legacy.php
+++ b/common/legacy.php
@@ -232,6 +232,7 @@ function getNextSequence(): int
 /**
  * Set Sequence number to session
  *
+ * @deprecated
  * @param int $seq sequence number
  * @return void
  */
@@ -248,6 +249,7 @@ function setUserSequence($seq): void
 /**
  * Check Sequence number grant
  *
+ * @deprecated
  * @param int $seq sequence number
  * @return bool
  */
@@ -313,6 +315,7 @@ function getNotEncodedUrl(): string
 /**
  * Get a encoded url. If url is encoded, not encode. Otherwise html encode the url.
  *
+ * @deprecated
  * @see getUrl()
  * @return string
  */
@@ -386,6 +389,7 @@ function getNotEncodedFullUrl(): string
  * getSiteUrl() returns the URL by transforming the given argument value of domain
  * The first argument should consist of domain("http://" not included) and path
  *
+ * @deprecated
  * @return string
  */
 function getSiteUrl(): string
@@ -408,6 +412,7 @@ function getSiteUrl(): string
  * getSiteUrl() returns the not encoded URL by transforming the given argument value of domain
  * The first argument should consist of domain("http://" not included) and path
  *
+ * @deprecated
  * @return string
  */
 function getNotEncodedSiteUrl(): string
@@ -429,6 +434,7 @@ function getNotEncodedSiteUrl(): string
 /**
  * Return the value adding request uri to the getSiteUrl() To get the full url
  *
+ * @deprecated
  * @return string
  */
 function getFullSiteUrl(): string
@@ -468,6 +474,7 @@ function getCurrentPageUrl($escape = true): string
 /**
  * Return if domain of the virtual site is url type or id type
  *
+ * @deprecated
  * @param string $domain
  * @return bool
  */
@@ -540,6 +547,7 @@ function cut_str($string, $cut_size = 0, $tail = '...'): string
 /**
  * Convert XE legacy time zone format into UTC offset.
  *
+ * @deprecated
  * @param string $time_zone Time zone in '+0900' format
  * @return int
  */
@@ -551,6 +559,7 @@ function get_time_zone_offset($timezone): int
 /**
  * Get the offset between the current user's time zone and Rhymix's internal time zone.
  *
+ * @param ?int $timestamp (optional)
  * @return int
  */
 function zgap($timestamp = null): int
@@ -771,6 +780,7 @@ function getMonthName(int $month, bool $short = true): string
 /**
  * Returns encoded value of given email address for email scraping
  *
+ * @deprecated
  * @param string $email The email
  * @return string
  */
@@ -804,6 +814,7 @@ function debugPrint($value, ...$values): void
 /**
  * Delete the second object vars from the first argument
  *
+ * @deprecated
  * @param object $target_obj An original object
  * @param object $del_obj Object vars to delete from the original object
  * @return object
@@ -826,6 +837,7 @@ function delObjectVars($target_obj, $del_obj): object
 /**
  * Delete variables that are commonly submitted but don't need to be saved.
  *
+ * @deprecated
  * @param array|object $vars
  * @return array|object
  */
@@ -871,6 +883,7 @@ function getNumberingPath($no, int $size = 3): string
 /**
  * Sanitize HTML content.
  *
+ * @deprecated
  * @param string $content Target content
  * @return string
  */
@@ -882,6 +895,7 @@ function removeHackTag($content): string
 /**
  * Get whether utf8 or not given string
  *
+ * @deprecated
  * @param string $string
  * @param bool $return_convert If set, returns converted string
  * @param bool $urldecode
@@ -909,17 +923,18 @@ function detectUTF8($string, $return_convert = FALSE, $urldecode = TRUE)
 /**
  * Get is current user crawler
  *
- * @param string $agent if set, use this value instead HTTP_USER_AGENT
+ * @param ?string $user_agent if set, use this value instead HTTP_USER_AGENT
  * @return bool
  */
-function isCrawler($agent = null): bool
+function isCrawler($user_agent = null): bool
 {
-	return Rhymix\Framework\UA::isRobot($agent);
+	return Rhymix\Framework\UA::isRobot($user_agent);
 }
 
 /**
  * Remove embed media for admin
  *
+ * @deprecated
  * @param string $content
  * @param int $writer_member_srl
  * @return void
@@ -960,6 +975,9 @@ function stripEmbedTagForAdmin(&$content, $writer_member_srl): void
 /**
  * Check for CSRF attacks
  *
+ * Use Rhymix\Framework\Security::checkCSRF() instead.
+ *
+ * @deprecated
  * @return bool
  */
 function checkCSRF(): bool
@@ -969,6 +987,8 @@ function checkCSRF(): bool
 
 /**
  * menu exposure check by isShow column
+ *
+ * @deprecated
  * @param array $menu
  * @return void
  */
@@ -994,6 +1014,7 @@ function recurciveExposureCheck(&$menu): void
 /**
  * Alias to hex2rgb()
  *
+ * @deprecated
  * @param string $hexstr
  * @return array
  */
@@ -1101,7 +1122,7 @@ if(!function_exists('mb_strlen'))
  */
 if(!function_exists('mb_strpos'))
 {
-	function mb_strpos($haystack, $needle, $offset, $charset = null)
+	function mb_strpos($haystack, $needle, $offset = 0, $charset = null)
 	{
 		if(function_exists('iconv_strpos'))
 		{
@@ -1239,6 +1260,7 @@ function reload($isOpener = FALSE): void
  * @param string $errstr
  * @param string $file
  * @param int $line
+ * @param array $context
  * @return void
  */
 function handleError($errno, $errstr, $file, $line, $context): void
diff --git a/tests/unit/functions/FunctionsTest.php b/tests/unit/functions/FunctionsTest.php
index 000fe451f..410221fa7 100644
--- a/tests/unit/functions/FunctionsTest.php
+++ b/tests/unit/functions/FunctionsTest.php
@@ -75,7 +75,7 @@ class FunctionsTest extends \Codeception\Test\Unit
 		$this->assertEquals(array('foo', 'bar,baz'), explode_with_escape(',', 'foo,bar\\,baz'));
 		$this->assertEquals(array('foo', 'bar\\', 'baz'), explode_with_escape(',', 'foo,bar\\ , baz'));
 		$this->assertEquals(array('foo', 'bar,baz', 'rhymix'), explode_with_escape(',', 'foo,bar\\,baz,rhymix'));
-		$this->assertEquals(array('foo', 'bar,baz'), explode_with_escape(',', 'foo,bar!,baz', null, '!'));
+		$this->assertEquals(array('foo', 'bar,baz'), explode_with_escape(',', 'foo,bar!,baz', 0, '!'));
 	}
 
 	public function testStartsEndsContains()