diff --git a/application/Espo/Core/Utils/DateTime.php b/application/Espo/Core/Utils/DateTime.php
index 0c73dc1591..6da7557f12 100644
--- a/application/Espo/Core/Utils/DateTime.php
+++ b/application/Espo/Core/Utils/DateTime.php
@@ -46,13 +46,13 @@ class DateTime
 
     public const SYSTEM_DATE_FORMAT = 'Y-m-d';
 
-    private ?string $dateFormat;
+    private string $dateFormat;
 
-    private ?string $timeFormat;
+    private string $timeFormat;
 
     private DateTimeZone $timezone;
 
-    private ?string $language;
+    private string $language;
 
     public function __construct(
         ?string $dateFormat = 'YYYY-MM-DD',
@@ -94,7 +94,7 @@ class DateTime
         string $string,
         ?string $format = null,
         ?string $language = null
-    ): ?string {
+    ): string {
 
         $dateTime = DateTimeStd::createFromFormat('Y-m-d', $string);
 
diff --git a/application/Espo/Core/Utils/File/Manager.php b/application/Espo/Core/Utils/File/Manager.php
index b2e267646d..409d4a87f7 100644
--- a/application/Espo/Core/Utils/File/Manager.php
+++ b/application/Espo/Core/Utils/File/Manager.php
@@ -978,6 +978,7 @@ class Manager
      */
     public function getDirName(string $path, bool $isFullPath = true, bool $useIsDir = true): string
     {
+        /** @var string */
         $dirName = preg_replace('/\/$/i', '', $path);
 
         $dirName = ($useIsDir && is_dir($dirName)) ?
@@ -1159,6 +1160,7 @@ class Manager
             $basePath .= $dirSeparator;
         }
 
+        /** @var string */
         return preg_replace('/^'. preg_quote($basePath, $dirSeparator) . '/', '', $path);
     }
 
diff --git a/application/Espo/Core/Utils/File/ZipArchive.php b/application/Espo/Core/Utils/File/ZipArchive.php
index bd434a11d8..9c53983a03 100644
--- a/application/Espo/Core/Utils/File/ZipArchive.php
+++ b/application/Espo/Core/Utils/File/ZipArchive.php
@@ -33,11 +33,11 @@ use Espo\Core\Exceptions\Error;
 
 class ZipArchive
 {
-    private $fileManager;
+    private Manager $fileManager;
 
-    public function __construct(Manager $fileManager = null)
+    public function __construct(?Manager $fileManager = null)
     {
-        if (!isset($fileManager)) {
+        if ($fileManager === null) {
             $fileManager = new Manager();
         }
 
diff --git a/application/Espo/Core/Utils/Language.php b/application/Espo/Core/Utils/Language.php
index 3ad7f1e785..b719ee23cc 100644
--- a/application/Espo/Core/Utils/Language.php
+++ b/application/Espo/Core/Utils/Language.php
@@ -58,7 +58,7 @@ class Language
      */
     private $changedData = [];
 
-    private ?string $currentLanguage = null;
+    private string $currentLanguage;
 
     protected string $defaultLanguage = 'en_US';
 
diff --git a/application/Espo/Core/Utils/Layout.php b/application/Espo/Core/Utils/Layout.php
index eeeeeb9df1..03b75cb587 100644
--- a/application/Espo/Core/Utils/Layout.php
+++ b/application/Espo/Core/Utils/Layout.php
@@ -113,6 +113,7 @@ class Layout
 
     protected function sanitizeInput(string $name): string
     {
+        /** @var string */
         return preg_replace("([\.]{2,})", '', $name);
     }
 }
diff --git a/application/Espo/Core/Utils/Metadata.php b/application/Espo/Core/Utils/Metadata.php
index 375e933452..30946fc829 100644
--- a/application/Espo/Core/Utils/Metadata.php
+++ b/application/Espo/Core/Utils/Metadata.php
@@ -145,6 +145,8 @@ class Metadata
             $this->init();
         }
 
+        assert($this->data !== null);
+
         return $this->data;
     }
 
@@ -175,6 +177,8 @@ class Metadata
             $this->init($reload);
         }
 
+        assert($this->data !== null);
+
         if ($isJSON) {
             return Json::encode($this->data);
         }
@@ -212,6 +216,8 @@ class Metadata
             $this->objInit($reload);
         }
 
+        assert($this->objData !== null);
+
         return $this->objData;
     }
 
diff --git a/application/Espo/Core/Utils/Module.php b/application/Espo/Core/Utils/Module.php
index 91a38c61a5..1beb2f90d5 100644
--- a/application/Espo/Core/Utils/Module.php
+++ b/application/Espo/Core/Utils/Module.php
@@ -101,6 +101,8 @@ class Module
             $this->init();
         }
 
+        assert($this->data !== null);
+
         if ($key === null) {
             return $this->data;
         }
@@ -110,7 +112,11 @@ class Module
 
     private function init(): void
     {
-        if ($this->useCache && $this->dataCache->has($this->cacheKey)) {
+        if (
+            $this->useCache &&
+            $this->dataCache &&
+            $this->dataCache->has($this->cacheKey)
+        ) {
             /** @var array<string,array<string,mixed>> */
             $data = $this->dataCache->get($this->cacheKey);
 
@@ -121,7 +127,7 @@ class Module
 
         $this->data = $this->loadData();
 
-        if ($this->useCache) {
+        if ($this->useCache && $this->dataCache) {
             $this->dataCache->store($this->cacheKey, $this->data);
         }
     }