diff --git a/system/CLI/Commands.php b/system/CLI/Commands.php
index 30bd2c26..21157141 100644
--- a/system/CLI/Commands.php
+++ b/system/CLI/Commands.php
@@ -125,7 +125,7 @@ public function discoverCommands()
                 /** @var BaseCommand $class */
                 $class = new $className($this->logger, $this);
 
-                if (isset($class->group)) {
+                if (isset($class->group) && ! isset($this->commands[$class->name])) {
                     $this->commands[$class->name] = [
                         'class'       => $className,
                         'file'        => $file,
diff --git a/system/CLI/GeneratorTrait.php b/system/CLI/GeneratorTrait.php
index 258f1237..065197be 100644
--- a/system/CLI/GeneratorTrait.php
+++ b/system/CLI/GeneratorTrait.php
@@ -516,7 +516,7 @@ protected function setEnabledSuffixing(bool $enabledSuffixing)
      * Gets a single command-line option. Returns TRUE if the option exists,
      * but doesn't have a value, and is simply acting as a flag.
      */
-    protected function getOption(string $name): string|bool|null
+    protected function getOption(string $name): bool|string|null
     {
         if (! array_key_exists($name, $this->params)) {
             return CLI::getOption($name);
diff --git a/system/Cache/Handlers/RedisHandler.php b/system/Cache/Handlers/RedisHandler.php
index 9e1003d1..22f4e435 100644
--- a/system/Cache/Handlers/RedisHandler.php
+++ b/system/Cache/Handlers/RedisHandler.php
@@ -175,18 +175,17 @@ public function delete(string $key)
      */
     public function deleteMatching(string $pattern)
     {
+        /** @var list<string> $matchedKeys */
         $matchedKeys = [];
+        $pattern     = static::validateKey($pattern, $this->prefix);
         $iterator    = null;
 
         do {
-            // Scan for some keys
+            /** @var false|list<string>|Redis $keys */
             $keys = $this->redis->scan($iterator, $pattern);
 
-            // Redis may return empty results, so protect against that
-            if ($keys !== false) {
-                foreach ($keys as $key) {
-                    $matchedKeys[] = $key;
-                }
+            if (is_array($keys)) {
+                $matchedKeys = [...$matchedKeys, ...$keys];
             }
         } while ($iterator > 0);
 
diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index 65f5dd22..95feae81 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -56,7 +56,7 @@ class CodeIgniter
     /**
      * The current version of CodeIgniter Framework
      */
-    public const CI_VERSION = '4.5.2';
+    public const CI_VERSION = '4.5.3';
 
     /**
      * App startup time.
@@ -353,7 +353,7 @@ public function run(?RouteCollectionInterface $routes = null, bool $returnRespon
         } else {
             try {
                 $this->response = $this->handleRequest($routes, config(Cache::class), $returnResponse);
-            } catch (ResponsableInterface|DeprecatedRedirectException $e) {
+            } catch (DeprecatedRedirectException|ResponsableInterface $e) {
                 $this->outputBufferingEnd();
                 if ($e instanceof DeprecatedRedirectException) {
                     $e = new RedirectException($e->getMessage(), $e->getCode(), $e);
diff --git a/system/Commands/Database/MigrateRollback.php b/system/Commands/Database/MigrateRollback.php
index f206d7fc..e1c788e7 100644
--- a/system/Commands/Database/MigrateRollback.php
+++ b/system/Commands/Database/MigrateRollback.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\CLI\BaseCommand;
 use CodeIgniter\CLI\CLI;
+use CodeIgniter\Database\MigrationRunner;
 use Throwable;
 
 /**
@@ -78,10 +79,23 @@ public function run(array $params)
             // @codeCoverageIgnoreEnd
         }
 
+        /** @var MigrationRunner $runner */
         $runner = service('migrations');
 
         try {
             $batch = $params['b'] ?? CLI::getOption('b') ?? $runner->getLastBatch() - 1;
+
+            if (is_string($batch)) {
+                if (! ctype_digit($batch)) {
+                    CLI::error('Invalid batch number: ' . $batch, 'light_gray', 'red');
+                    CLI::newLine();
+
+                    return EXIT_ERROR;
+                }
+
+                $batch = (int) $batch;
+            }
+
             CLI::write(lang('Migrations.rollingBack') . ' ' . $batch, 'yellow');
 
             if (! $runner->regress($batch)) {
diff --git a/system/Commands/Database/ShowTableInfo.php b/system/Commands/Database/ShowTableInfo.php
index 05dcfe4d..147b6eb6 100644
--- a/system/Commands/Database/ShowTableInfo.php
+++ b/system/Commands/Database/ShowTableInfo.php
@@ -188,6 +188,11 @@ private function restoreDBPrefix(): void
         $this->db->setPrefix($this->DBPrefix);
     }
 
+    /**
+     * Show Data of Table
+     *
+     * @return void
+     */
     private function showDataOfTable(string $tableName, int $limitRows, int $limitFieldValue)
     {
         CLI::write("Data of Table \"{$tableName}\":", 'black', 'yellow');
@@ -207,6 +212,13 @@ private function showDataOfTable(string $tableName, int $limitRows, int $limitFi
         CLI::table($this->tbody, $thead);
     }
 
+    /**
+     * Show All Tables
+     *
+     * @param list<string> $tables
+     *
+     * @return void
+     */
     private function showAllTables(array $tables)
     {
         CLI::write('The following is a list of the names of all database tables:', 'black', 'yellow');
@@ -219,6 +231,13 @@ private function showAllTables(array $tables)
         CLI::newLine();
     }
 
+    /**
+     * Make body for table
+     *
+     * @param list<string> $tables
+     *
+     * @return list<list<int|string>>
+     */
     private function makeTbodyForShowAllTables(array $tables): array
     {
         $this->removeDBPrefix();
@@ -244,6 +263,11 @@ private function makeTbodyForShowAllTables(array $tables): array
         return $this->tbody;
     }
 
+    /**
+     * Make table rows
+     *
+     * @return list<list<int|string>>
+     */
     private function makeTableRows(
         string $tableName,
         int $limitRows,
diff --git a/system/Commands/ListCommands.php b/system/Commands/ListCommands.php
index 778f8f95..87c3e96b 100644
--- a/system/Commands/ListCommands.php
+++ b/system/Commands/ListCommands.php
@@ -85,6 +85,8 @@ public function run(array $params)
 
     /**
      * Lists the commands with accompanying info.
+     *
+     * @return void
      */
     protected function listFull(array $commands)
     {
@@ -126,6 +128,8 @@ protected function listFull(array $commands)
 
     /**
      * Lists the commands only.
+     *
+     * @return void
      */
     protected function listSimple(array $commands)
     {
diff --git a/system/Commands/Server/Serve.php b/system/Commands/Server/Serve.php
index c32cd656..82e58998 100644
--- a/system/Commands/Server/Serve.php
+++ b/system/Commands/Server/Serve.php
@@ -103,7 +103,7 @@ public function run(array $params)
         $docroot = escapeshellarg(FCPATH);
 
         // Mimic Apache's mod_rewrite functionality with user settings.
-        $rewrite = escapeshellarg(__DIR__ . '/rewrite.php');
+        $rewrite = escapeshellarg(SYSTEMPATH . 'rewrite.php');
 
         // Call PHP's built-in webserver, making sure to set our
         // base path to the public folder, and to use the rewrite file
diff --git a/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollector.php b/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollector.php
index 8cbd81fb..0d426a3b 100644
--- a/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollector.php
+++ b/system/Commands/Utilities/Routes/AutoRouterImproved/AutoRouteCollector.php
@@ -27,6 +27,7 @@ final class AutoRouteCollector
      * @param string             $namespace            namespace to search
      * @param list<class-string> $protectedControllers List of controllers in Defined
      *                                                 Routes that should not be accessed via Auto-Routing.
+     * @param list<string>       $httpMethods
      * @param string             $prefix               URI prefix for Module Routing
      */
     public function __construct(
@@ -91,6 +92,13 @@ public function get(): array
         return $tbody;
     }
 
+    /**
+     * Adding Filters
+     *
+     * @param list<array<string, array|string>> $routes
+     *
+     * @return list<array<string, array|string>>
+     */
     private function addFilters($routes)
     {
         $filterCollector = new FilterCollector(true);
diff --git a/system/Commands/Utilities/Routes/FilterFinder.php b/system/Commands/Utilities/Routes/FilterFinder.php
index 82ea2697..7971e5c1 100644
--- a/system/Commands/Utilities/Routes/FilterFinder.php
+++ b/system/Commands/Utilities/Routes/FilterFinder.php
@@ -15,6 +15,7 @@
 
 use CodeIgniter\Exceptions\PageNotFoundException;
 use CodeIgniter\Filters\Filters;
+use CodeIgniter\HTTP\Exceptions\BadRequestException;
 use CodeIgniter\HTTP\Exceptions\RedirectException;
 use CodeIgniter\Router\Router;
 use Config\Feature;
@@ -72,7 +73,7 @@ public function find(string $uri): array
                 'before' => [],
                 'after'  => [],
             ];
-        } catch (PageNotFoundException) {
+        } catch (BadRequestException|PageNotFoundException) {
             return [
                 'before' => ['<unknown>'],
                 'after'  => ['<unknown>'],
diff --git a/system/Config/BaseService.php b/system/Config/BaseService.php
index cd770dc6..5bd55403 100644
--- a/system/Config/BaseService.php
+++ b/system/Config/BaseService.php
@@ -346,6 +346,8 @@ public static function serviceExists(string $name): ?string
      * Reset shared instances and mocks for testing.
      *
      * @return void
+     *
+     * @testTag only available to test code
      */
     public static function reset(bool $initAutoloader = true)
     {
@@ -362,6 +364,8 @@ public static function reset(bool $initAutoloader = true)
      * Resets any mock and shared instances for a single service.
      *
      * @return void
+     *
+     * @testTag only available to test code
      */
     public static function resetSingle(string $name)
     {
@@ -375,6 +379,8 @@ public static function resetSingle(string $name)
      * @param object $mock
      *
      * @return void
+     *
+     * @testTag only available to test code
      */
     public static function injectMock(string $name, $mock)
     {
diff --git a/system/Database/BaseBuilder.php b/system/Database/BaseBuilder.php
index f9ca1efd..4e6e422b 100644
--- a/system/Database/BaseBuilder.php
+++ b/system/Database/BaseBuilder.php
@@ -1448,11 +1448,12 @@ public function orHaving($key, $value = null, ?bool $escape = null)
      */
     public function orderBy(string $orderBy, string $direction = '', ?bool $escape = null)
     {
-        $qbOrderBy = [];
         if ($orderBy === '') {
             return $this;
         }
 
+        $qbOrderBy = [];
+
         $direction = strtoupper(trim($direction));
 
         if ($direction === 'RANDOM') {
@@ -1463,7 +1464,7 @@ public function orderBy(string $orderBy, string $direction = '', ?bool $escape =
             $direction = in_array($direction, ['ASC', 'DESC'], true) ? ' ' . $direction : '';
         }
 
-        if (! is_bool($escape)) {
+        if ($escape === null) {
             $escape = $this->db->protectIdentifiers;
         }
 
@@ -1474,8 +1475,6 @@ public function orderBy(string $orderBy, string $direction = '', ?bool $escape =
                 'escape'    => false,
             ];
         } else {
-            $qbOrderBy = [];
-
             foreach (explode(',', $orderBy) as $field) {
                 $qbOrderBy[] = ($direction === '' && preg_match('/\s+(ASC|DESC)$/i', rtrim($field), $match, PREG_OFFSET_CAPTURE))
                     ? [
diff --git a/system/Database/BaseConnection.php b/system/Database/BaseConnection.php
index 57c37d8a..6581dc7c 100644
--- a/system/Database/BaseConnection.php
+++ b/system/Database/BaseConnection.php
@@ -477,6 +477,8 @@ public function initialize()
 
     /**
      * Close the database connection.
+     *
+     * @return void
      */
     public function close()
     {
@@ -736,6 +738,8 @@ public function simpleQuery(string $sql)
      * Disable Transactions
      *
      * This permits transactions to be disabled at run-time.
+     *
+     * @return void
      */
     public function transOff()
     {
@@ -1454,7 +1458,7 @@ protected function getDriverFunctionPrefix(): string
     /**
      * Returns an array of table names
      *
-     * @return array|false
+     * @return false|list<string>
      *
      * @throws DatabaseException
      */
@@ -1481,6 +1485,7 @@ public function listTables(bool $constrainByPrefix = false)
         $query = $this->query($sql);
 
         foreach ($query->getResultArray() as $row) {
+            /** @var string $table */
             $table = $row['table_name'] ?? $row['TABLE_NAME'] ?? $row[array_key_first($row)];
 
             $this->dataCache['table_names'][] = $table;
@@ -1531,7 +1536,7 @@ public function tableExists(string $tableName, bool $cached = true): bool
     /**
      * Fetch Field Names
      *
-     * @return array|false
+     * @return false|list<string>
      *
      * @throws DatabaseException
      */
@@ -1608,7 +1613,7 @@ public function getIndexData(string $table)
     /**
      * Returns an object with foreign key data
      *
-     * @return array
+     * @return array<string, stdClass>
      */
     public function getForeignKeyData(string $table)
     {
@@ -1769,7 +1774,9 @@ abstract protected function _listColumns(string $table = '');
     /**
      * Platform-specific field data information.
      *
-     * @see    getFieldData()
+     * @see getFieldData()
+     *
+     * @return list<stdClass>
      */
     abstract protected function _fieldData(string $table): array;
 
diff --git a/system/Database/MySQLi/Connection.php b/system/Database/MySQLi/Connection.php
index b25f2e1a..068dfba5 100644
--- a/system/Database/MySQLi/Connection.php
+++ b/system/Database/MySQLi/Connection.php
@@ -237,6 +237,8 @@ public function connect(bool $persistent = false)
     /**
      * Keep or establish the connection if no queries have been sent for
      * a length of time exceeding the server's idle timeout.
+     *
+     * @return void
      */
     public function reconnect()
     {
diff --git a/system/Database/OCI8/Connection.php b/system/Database/OCI8/Connection.php
index be7eb37c..f7983a69 100644
--- a/system/Database/OCI8/Connection.php
+++ b/system/Database/OCI8/Connection.php
@@ -104,6 +104,10 @@ class Connection extends BaseConnection
      */
     private function isValidDSN(): bool
     {
+        if ($this->DSN === null || $this->DSN === '') {
+            return false;
+        }
+
         foreach ($this->validDSNs as $regexp) {
             if (preg_match($regexp, $this->DSN)) {
                 return true;
@@ -120,13 +124,13 @@ private function isValidDSN(): bool
      */
     public function connect(bool $persistent = false)
     {
-        if (empty($this->DSN) && ! $this->isValidDSN()) {
+        if (! $this->isValidDSN()) {
             $this->buildDSN();
         }
 
         $func = $persistent ? 'oci_pconnect' : 'oci_connect';
 
-        return empty($this->charset)
+        return ($this->charset === '')
             ? $func($this->username, $this->password, $this->DSN)
             : $func($this->username, $this->password, $this->DSN, $this->charset);
     }
@@ -632,7 +636,7 @@ protected function buildDSN()
         }
 
         $isEasyConnectableHostName = $this->hostname !== '' && ! str_contains($this->hostname, '/') && ! str_contains($this->hostname, ':');
-        $easyConnectablePort       = ! empty($this->port) && ctype_digit($this->port) ? ':' . $this->port : '';
+        $easyConnectablePort       = ($this->port !== '') && ctype_digit((string) $this->port) ? ':' . $this->port : '';
         $easyConnectableDatabase   = $this->database !== '' ? '/' . ltrim($this->database, '/') : '';
 
         if ($isEasyConnectableHostName && ($easyConnectablePort !== '' || $easyConnectableDatabase !== '')) {
diff --git a/system/Database/Postgre/Connection.php b/system/Database/Postgre/Connection.php
index c22dc860..d3af2380 100644
--- a/system/Database/Postgre/Connection.php
+++ b/system/Database/Postgre/Connection.php
@@ -104,6 +104,8 @@ public function connect(bool $persistent = false)
 
     /**
      * Converts the DSN with semicolon syntax.
+     *
+     * @return void
      */
     private function convertDSN()
     {
@@ -143,6 +145,8 @@ private function convertDSN()
     /**
      * Keep or establish the connection if no queries have been sent for
      * a length of time exceeding the server's idle timeout.
+     *
+     * @return void
      */
     public function reconnect()
     {
diff --git a/system/Database/SQLSRV/Connection.php b/system/Database/SQLSRV/Connection.php
index 0626a63c..7e008e27 100644
--- a/system/Database/SQLSRV/Connection.php
+++ b/system/Database/SQLSRV/Connection.php
@@ -164,6 +164,8 @@ public function getAllErrorMessages(): string
     /**
      * Keep or establish the connection if no queries have been sent for
      * a length of time exceeding the server's idle timeout.
+     *
+     * @return void
      */
     public function reconnect()
     {
diff --git a/system/Database/SQLite3/Connection.php b/system/Database/SQLite3/Connection.php
index 94543418..9945d41d 100644
--- a/system/Database/SQLite3/Connection.php
+++ b/system/Database/SQLite3/Connection.php
@@ -55,6 +55,9 @@ class Connection extends BaseConnection
      */
     protected $busyTimeout;
 
+    /**
+     * @return void
+     */
     public function initialize()
     {
         parent::initialize();
@@ -101,6 +104,8 @@ public function connect(bool $persistent = false)
     /**
      * Keep or establish the connection if no queries have been sent for
      * a length of time exceeding the server's idle timeout.
+     *
+     * @return void
      */
     public function reconnect()
     {
@@ -211,7 +216,7 @@ protected function _listColumns(string $table = ''): string
     }
 
     /**
-     * @return array|false
+     * @return false|list<string>
      *
      * @throws DatabaseException
      */
diff --git a/system/Router/AutoRouterImproved.php b/system/Router/AutoRouterImproved.php
index 0db5ebc1..63cdd770 100644
--- a/system/Router/AutoRouterImproved.php
+++ b/system/Router/AutoRouterImproved.php
@@ -162,7 +162,7 @@ private function searchFirstController(): bool
             $segment = array_shift($segments);
             $controllerPos++;
 
-            $class = $this->translateURIDashes($segment);
+            $class = $this->translateURI($segment);
 
             // as soon as we encounter any segment that is not PSR-4 compliant, stop searching
             if (! $this->isValidSegment($class)) {
@@ -209,7 +209,7 @@ private function searchLastDefaultController(): bool
             }
 
             $namespaces = array_map(
-                fn ($segment) => $this->translateURIDashes($segment),
+                fn ($segment) => $this->translateURI($segment),
                 $segments
             );
 
@@ -307,7 +307,7 @@ public function getRoute(string $uri, string $httpVerb): array
 
         $method = '';
         if ($methodParam !== null) {
-            $method = $httpVerb . $this->translateURIDashes($methodParam);
+            $method = $httpVerb . $this->translateURI($methodParam);
 
             $this->checkUriForMethod($method);
         }
@@ -519,7 +519,17 @@ private function checkUriForMethod(string $method): void
             return;
         }
 
-        if (! in_array($method, get_class_methods($this->controller), true)) {
+        if (
+            // For example, if `getSomeMethod()` exists in the controller, only
+            // the URI `controller/some-method` should be accessible. But if a
+            // visitor navigates to the URI `controller/somemethod`, `getSomemethod()`
+            // will be checked, and `method_exists()` will return true because
+            // method names in PHP are case-insensitive.
+            method_exists($this->controller, $method)
+            // But we do not permit `controller/somemethod`, so check the exact
+            // method name.
+            && ! in_array($method, get_class_methods($this->controller), true)
+        ) {
             throw new PageNotFoundException(
                 '"' . $this->controller . '::' . $method . '()" is not found.'
             );
@@ -536,7 +546,10 @@ private function isValidSegment(string $segment): bool
         return (bool) preg_match('/^[a-zA-Z_\x80-\xff][a-zA-Z0-9_\x80-\xff]*$/', $segment);
     }
 
-    private function translateURIDashes(string $segment): string
+    /**
+     * Translates URI segment to CamelCase or replaces `-` with `_`.
+     */
+    private function translateURI(string $segment): string
     {
         if ($this->translateUriToCamelCase) {
             if (strtolower($segment) !== $segment) {
diff --git a/system/Router/DefinedRouteCollector.php b/system/Router/DefinedRouteCollector.php
index 8d4f1dc5..2452a141 100644
--- a/system/Router/DefinedRouteCollector.php
+++ b/system/Router/DefinedRouteCollector.php
@@ -38,6 +38,10 @@ public function collect(): Generator
             $routes = $this->routeCollection->getRoutes($method);
 
             foreach ($routes as $route => $handler) {
+                // The route key should be a string, but it is stored as an array key,
+                // it might be an integer.
+                $route = (string) $route;
+
                 if (is_string($handler) || $handler instanceof Closure) {
                     if ($handler instanceof Closure) {
                         $view = $this->routeCollection->getRoutesOptions($route, $method)['view'] ?? false;
diff --git a/system/Router/Router.php b/system/Router/Router.php
index de996f53..dc778cd0 100644
--- a/system/Router/Router.php
+++ b/system/Router/Router.php
@@ -187,6 +187,7 @@ public function __construct(RouteCollectionInterface $routes, ?Request $request
      *
      * @return (Closure(mixed...): (ResponseInterface|string|void))|string Controller classname or Closure
      *
+     * @throws BadRequestException
      * @throws PageNotFoundException
      * @throws RedirectException
      */
diff --git a/system/Test/Mock/MockConnection.php b/system/Test/Mock/MockConnection.php
index 020d6e3d..ed814240 100644
--- a/system/Test/Mock/MockConnection.php
+++ b/system/Test/Mock/MockConnection.php
@@ -38,6 +38,11 @@ class MockConnection extends BaseConnection
     public $database;
     public $lastQuery;
 
+    /**
+     * @param mixed $return
+     *
+     * @return $this
+     */
     public function shouldReturn(string $method, $return)
     {
         $this->returnValues[$method] = $return;
@@ -127,13 +132,13 @@ public function reconnect(): bool
     /**
      * Select a specific database table to use.
      *
-     * @return mixed
+     * @return bool
      */
     public function setDatabase(string $databaseName)
     {
         $this->database = $databaseName;
 
-        return $this;
+        return true;
     }
 
     /**
diff --git a/system/Validation/Validation.php b/system/Validation/Validation.php
index eb87ef3f..bfc661c2 100644
--- a/system/Validation/Validation.php
+++ b/system/Validation/Validation.php
@@ -399,8 +399,10 @@ private function processIfExist(string $field, array $rules, array $data)
                         break;
                     }
                 }
-            } else {
+            } elseif (str_contains($field, '.')) {
                 $dataIsExisting = array_key_exists($ifExistField, $flattenedData);
+            } else {
+                $dataIsExisting = array_key_exists($ifExistField, $data);
             }
 
             if (! $dataIsExisting) {
diff --git a/system/Commands/Server/rewrite.php b/system/rewrite.php
similarity index 93%
rename from system/Commands/Server/rewrite.php
rename to system/rewrite.php
index f936cd63..aba45604 100644
--- a/system/Commands/Server/rewrite.php
+++ b/system/rewrite.php
@@ -21,11 +21,6 @@
  */
 
 // @codeCoverageIgnoreStart
-// Avoid this file run when listing commands
-if (PHP_SAPI === 'cli') {
-    return;
-}
-
 $uri = urldecode(
     parse_url('https://codeigniter.com' . $_SERVER['REQUEST_URI'], PHP_URL_PATH) ?? ''
 );