diff --git a/app/Views/errors/cli/error_exception.php b/app/Views/errors/cli/error_exception.php
index 983cb8885140..b49244f5a054 100644
--- a/app/Views/errors/cli/error_exception.php
+++ b/app/Views/errors/cli/error_exception.php
@@ -33,7 +33,7 @@
     foreach ($backtraces as $i => $error) {
         $padFile  = '    '; // 4 spaces
         $padClass = '       '; // 7 spaces
-        $c        = str_pad($i + 1, 3, ' ', STR_PAD_LEFT);
+        $c        = str_pad((string) ($i + 1), 3, ' ', STR_PAD_LEFT);
 
         if (isset($error['file'])) {
             $filepath = clean_path($error['file']) . ':' . $error['line'];
diff --git a/system/Cache/Handlers/FileHandler.php b/system/Cache/Handlers/FileHandler.php
index 4d16bbffac2f..ab0e51c289a4 100644
--- a/system/Cache/Handlers/FileHandler.php
+++ b/system/Cache/Handlers/FileHandler.php
@@ -204,7 +204,7 @@ protected function getItem(string $filename): array|false
         }
 
         try {
-            $data = unserialize($content, ['allowed_classes' => false]);
+            $data = unserialize($content, ['allowed_classes' => true]);
         } catch (Throwable) {
             return false;
         }
diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index 1c638d58e88e..b2cbbf802f29 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/system/Config/BaseConfig.php b/system/Config/BaseConfig.php
index 19ccbdb653e4..6bc983f67a82 100644
--- a/system/Config/BaseConfig.php
+++ b/system/Config/BaseConfig.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
@@ -190,7 +188,7 @@ protected function initEnvValue(&$property, string $name, string $prefix, string
                 return;
             }
 
-            $value = trim($value, '\'"');
+            $value = trim((string) $value, '\'"');
 
             if (is_int($property)) {
                 $value = (int) $value;
diff --git a/system/Test/ControllerTestTrait.php b/system/Test/ControllerTestTrait.php
index 7ecbc128d20c..2a7be526383d 100644
--- a/system/Test/ControllerTestTrait.php
+++ b/system/Test/ControllerTestTrait.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/system/View/Filters.php b/system/View/Filters.php
index c74e385cdb96..1f2cc1da80b9 100644
--- a/system/View/Filters.php
+++ b/system/View/Filters.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/system/View/Parser.php b/system/View/Parser.php
index 94e3bad97e35..85d0ff8468db 100644
--- a/system/View/Parser.php
+++ b/system/View/Parser.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/tests/_support/Commands/Foobar.php b/tests/_support/Commands/Foobar.php
index da49353ff009..edd0c769590e 100644
--- a/tests/_support/Commands/Foobar.php
+++ b/tests/_support/Commands/Foobar.php
@@ -11,8 +11,8 @@
  * the LICENSE file that was distributed with this source code.
  */
 
-use CodeIgniter\CLI\CLI;
 use Config\App;
+use CodeIgniter\CLI\CLI;
 
 return [
     'foo' => 'The command will use this as foo.',
diff --git a/tests/_support/Controllers/Newautorouting.php b/tests/_support/Controllers/Newautorouting.php
index 30d89c2db30e..2c31547ed2de 100644
--- a/tests/_support/Controllers/Newautorouting.php
+++ b/tests/_support/Controllers/Newautorouting.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=1);
-
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/tests/system/Cache/Handlers/PredisHandlerTest.php b/tests/system/Cache/Handlers/PredisHandlerTest.php
index 135d3ff083de..3e519b63651b 100644
--- a/tests/system/Cache/Handlers/PredisHandlerTest.php
+++ b/tests/system/Cache/Handlers/PredisHandlerTest.php
@@ -45,6 +45,7 @@ protected function setUp(): void
 
         $this->config  = new Cache();
         $this->handler = CacheFactory::getHandler($this->config, 'predis');
+        $this->handler->clean();
     }
 
     protected function tearDown(): void
diff --git a/tests/system/Debug/ExceptionsTest.php b/tests/system/Debug/ExceptionsTest.php
index 69e062671b7a..2e06add612f7 100644
--- a/tests/system/Debug/ExceptionsTest.php
+++ b/tests/system/Debug/ExceptionsTest.php
@@ -67,8 +67,8 @@ public function testDeprecationsOnPhp81DoNotThrow(): void
         $this->exception->initialize();
 
         try {
-            $result = str_contains('foobar', null); // @phpstan-ignore argument.type (Needed for testing)
-            $this->assertLogContains('error', '[DEPRECATED] str_contains(): ');
+            @trigger_error('Hello! I am a deprecation!', E_USER_DEPRECATED);
+            $this->assertLogContains('error', '[DEPRECATED] Hello! I am a deprecation!');
         } catch (ErrorException) {
             $this->fail('The catch block should not be reached.');
         } finally {