diff --git a/composer.json b/composer.json
index 9cabb129ff8c..27b87b9e709c 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,7 @@
         "phpunit/phpcov": "^9.0.2 || ^10.0",
         "phpunit/phpunit": "^10.5.16 || ^11.2",
         "predis/predis": "^3.0",
-        "rector/rector": "2.5.8",
+        "rector/rector": "2.5.9",
         "shipmonk/phpstan-baseline-per-identifier": "^2.0"
     },
     "replace": {
diff --git a/rector.php b/rector.php
index cd5f3c21dd0f..856952b19206 100644
--- a/rector.php
+++ b/rector.php
@@ -33,10 +33,7 @@
 use Rector\Php70\Rector\FuncCall\RandomFunctionRector;
 use Rector\Php71\Rector\FuncCall\RemoveExtraParametersRector;
 use Rector\Php80\Rector\Class_\ClassPropertyAssignToConstructorPromotionRector;
-use Rector\Php81\Rector\FuncCall\NullToStrictStringFuncCallArgRector;
-use Rector\Php81\Rector\Property\ReadOnlyPropertyRector;
 use Rector\PHPUnit\CodeQuality\Rector\Class_\YieldDataProviderRector;
-use Rector\PHPUnit\CodeQuality\Rector\FuncCall\AssertFuncCallToPHPUnitAssertRector;
 use Rector\PHPUnit\CodeQuality\Rector\StmtsAwareInterface\DeclareStrictTypesTestsRector;
 use Rector\Privatization\Rector\Class_\FinalizeTestCaseClassRector;
 use Rector\Privatization\Rector\Property\PrivatizeFinalClassPropertyRector;
@@ -107,13 +104,6 @@
         // Keep property defaults for backward compatibility.
         RemoveDefaultValueFromAssignedPropertyRector::class,
 
-        ReadOnlyPropertyRector::class => [
-            __DIR__ . '/system/Cache/ResponseCache.php',
-            __DIR__ . '/system/HotReloader/IteratorFilter.php',
-            __DIR__ . '/system/Router/RouteCollection.php',
-            __DIR__ . '/system/Security/Security.php',
-        ],
-
         // Exclude test file because `is_cli()` is mocked and Rector might remove needed parameters.
         RemoveExtraParametersRector::class => [
             __DIR__ . '/tests/system/Debug/ToolbarTest.php',
@@ -160,19 +150,11 @@
             __DIR__ . '/system/HTTP/SiteURI.php',
         ],
 
-        // Unnecessary (string) is inserted
-        NullToStrictStringFuncCallArgRector::class,
-
         CompactToVariablesRector::class,
 
         // possibly isset() on purpose, on updated Config classes property across versions
         IssetOnPropertyObjectToPropertyExistsRector::class,
 
-        AssertFuncCallToPHPUnitAssertRector::class => [
-            // use $this inside static closure
-            __DIR__ . '/tests/system/AutoReview/FrameworkCodeTest.php',
-        ],
-
         // some tests extended by other tests
         FinalizeTestCaseClassRector::class,
 
diff --git a/system/Router/Router.php b/system/Router/Router.php
index 063bb5074cbb..1eda4c616d62 100644
--- a/system/Router/Router.php
+++ b/system/Router/Router.php
@@ -694,7 +694,7 @@ private function isValidSegment(string $segment): bool
      * Takes an array of URI segments as input and sets the class/method
      * to be called.
      *
-     * @param array $segments URI segments
+     * @param list<string> $segments URI segments
      *
      * @return void
      */
@@ -705,13 +705,13 @@ protected function setRequest(array $segments = [])
             return;
         }
 
-        [$controller, $method] = array_pad(explode('::', $segments[0]), 2, null);
+        [$controller, $method] = explode('::', $segments[0], 2) + [null, null];
 
         $this->controller = $controller;
 
         // $this->method already contains the default method name,
         // so don't overwrite it with emptiness.
-        if (! empty($method)) {
+        if ($method !== null && $method !== '') {
             $this->method = $method;
         }
 
diff --git a/utils/phpstan-baseline/empty.notAllowed.neon b/utils/phpstan-baseline/empty.notAllowed.neon
index 796292761d9c..9060c95a91ec 100644
--- a/utils/phpstan-baseline/empty.notAllowed.neon
+++ b/utils/phpstan-baseline/empty.notAllowed.neon
@@ -1,4 +1,4 @@
-# total 205 errors
+# total 204 errors
 
 parameters:
     ignoreErrors:
@@ -279,7 +279,7 @@ parameters:
 
         -
             message: '#^Construct empty\(\) is not allowed\. Use more strict comparison\.$#'
-            count: 2
+            count: 1
             path: ../../system/Router/Router.php
 
         -
diff --git a/utils/phpstan-baseline/loader.neon b/utils/phpstan-baseline/loader.neon
index 03e4965a51a4..32ad4dacc2f5 100644
--- a/utils/phpstan-baseline/loader.neon
+++ b/utils/phpstan-baseline/loader.neon
@@ -1,4 +1,4 @@
-# total 1810 errors
+# total 1808 errors
 
 includes:
     - argument.type.neon
diff --git a/utils/phpstan-baseline/missingType.iterableValue.neon b/utils/phpstan-baseline/missingType.iterableValue.neon
index 677e7101b2c3..28aeaabd8f58 100644
--- a/utils/phpstan-baseline/missingType.iterableValue.neon
+++ b/utils/phpstan-baseline/missingType.iterableValue.neon
@@ -1,4 +1,4 @@
-# total 1140 errors
+# total 1139 errors
 
 parameters:
     ignoreErrors:
@@ -3637,11 +3637,6 @@ parameters:
             count: 1
             path: ../../system/Router/Router.php
 
-        -
-            message: '#^Method CodeIgniter\\Router\\Router\:\:setRequest\(\) has parameter \$segments with no value type specified in iterable type array\.$#'
-            count: 1
-            path: ../../system/Router/Router.php
-
         -
             message: '#^Method CodeIgniter\\Router\\Router\:\:validateRequest\(\) has parameter \$segments with no value type specified in iterable type array\.$#'
             count: 1