diff --git a/phpstan-baseline.php b/phpstan-baseline.php
index 1516c5d6f7c9..cac41a7dbfdb 100644
--- a/phpstan-baseline.php
+++ b/phpstan-baseline.php
@@ -226,71 +226,6 @@
 	'count' => 6,
 	'path' => __DIR__ . '/system/CodeIgniter.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:bootstrapEnvironment\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:callExit\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:detectEnvironment\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:forceSecureAccess\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:gatherOutput\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:getRequestObject\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:getResponseObject\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:initialize\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:initializeKint\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:resolvePlatformExtensions\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:spoofRequestMethod\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:startBenchmark\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\CodeIgniter\\:\\:storePreviousURL\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/CodeIgniter.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Only booleans are allowed in an if condition, CodeIgniter\\\\HTTP\\\\ResponseInterface\\|null given\\.$#',
 	'count' => 1,
@@ -3811,11 +3746,6 @@
 	'count' => 2,
 	'path' => __DIR__ . '/system/Test/Mock/MockCache.php',
 ];
-$ignoreErrors[] = [
-	'message' => '#^Method CodeIgniter\\\\Test\\\\Mock\\\\MockCodeIgniter\\:\\:callExit\\(\\) has no return type specified\\.$#',
-	'count' => 1,
-	'path' => __DIR__ . '/system/Test/Mock/MockCodeIgniter.php',
-];
 $ignoreErrors[] = [
 	'message' => '#^Cannot access property \\$insert_id on object\\|resource\\|false\\.$#',
 	'count' => 1,
diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index e017d6b9ccc2..4bde1c042b6d 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -198,6 +198,8 @@ public function __construct(App $config)
 
     /**
      * Handles some basic app and environment setup.
+     *
+     * @return void
      */
     public function initialize()
     {
@@ -224,6 +226,8 @@ public function initialize()
     /**
      * Checks system for missing required PHP extensions.
      *
+     * @return void
+     *
      * @throws FrameworkException
      *
      * @codeCoverageIgnore
@@ -251,6 +255,8 @@ protected function resolvePlatformExtensions()
 
     /**
      * Initializes Kint
+     *
+     * @return void
      */
     protected function initializeKint()
     {
@@ -564,6 +570,8 @@ protected function handleRequest(?RouteCollectionInterface $routes, Cache $cache
      *
      * @codeCoverageIgnore
      *
+     * @return void
+     *
      * @deprecated 4.4.0 No longer used. Moved to index.php and spark.
      */
     protected function detectEnvironment()
@@ -579,6 +587,8 @@ protected function detectEnvironment()
      *
      * If no boot file exists, we shouldn't continue because something
      * is wrong. At the very least, they should have error reporting setup.
+     *
+     * @return void
      */
     protected function bootstrapEnvironment()
     {
@@ -599,6 +609,8 @@ protected function bootstrapEnvironment()
      *
      * The timer is used to display total script execution both in the
      * debug toolbar, and potentially on the displayed page.
+     *
+     * @return void
      */
     protected function startBenchmark()
     {
@@ -628,6 +640,8 @@ public function setRequest($request)
 
     /**
      * Get our Request object, (either IncomingRequest or CLIRequest).
+     *
+     * @return void
      */
     protected function getRequestObject()
     {
@@ -647,6 +661,8 @@ protected function getRequestObject()
     /**
      * Get our Response object, and set some default values, including
      * the HTTP protocol version and a default successful response.
+     *
+     * @return void
      */
     protected function getResponseObject()
     {
@@ -669,6 +685,8 @@ protected function getResponseObject()
      *
      * @param int $duration How long the Strict Transport Security
      *                      should be enforced for this URL.
+     *
+     * @return void
      */
     protected function forceSecureAccess($duration = 31_536_000)
     {
@@ -978,6 +996,8 @@ protected function display404errors(PageNotFoundException $e)
      * @param ResponseInterface|string|null $returned
      *
      * @deprecated $cacheConfig is deprecated.
+     *
+     * @return void
      */
     protected function gatherOutput(?Cache $cacheConfig = null, $returned = null)
     {
@@ -1014,6 +1034,8 @@ protected function gatherOutput(?Cache $cacheConfig = null, $returned = null)
      * This helps provider safer, more reliable previous_url() detection.
      *
      * @param string|URI $uri
+     *
+     * @return void
      */
     public function storePreviousURL($uri)
     {
@@ -1055,6 +1077,8 @@ public function storePreviousURL($uri)
     /**
      * Modifies the Request Object to use a different method if a POST
      * variable called _method is found.
+     *
+     * @return void
      */
     public function spoofRequestMethod()
     {
@@ -1096,6 +1120,8 @@ protected function sendResponse()
      * @param int $code
      *
      * @deprecated 4.4.0 No longer Used. Moved to index.php.
+     *
+     * @return void
      */
     protected function callExit($code)
     {