diff --git a/application/Espo/Core/Action/ActionFactory.php b/application/Espo/Core/Action/ActionFactory.php
index 386bc21ec0..2534de0632 100644
--- a/application/Espo/Core/Action/ActionFactory.php
+++ b/application/Espo/Core/Action/ActionFactory.php
@@ -38,9 +38,9 @@ use Espo\Core\{
 
 class ActionFactory
 {
-    private $metadata;
+    private Metadata $metadata;
 
-    private $injectableFactory;
+    private InjectableFactory $injectableFactory;
 
     public function __construct(Metadata $metadata, InjectableFactory $injectableFactory)
     {
@@ -63,6 +63,11 @@ class ActionFactory
         return $this->injectableFactory->create($className);
     }
 
+    /**
+     * @param array<string,object> $with
+     * @deprecated
+     * @todo Remove.
+     */
     public function createWith(string $action, ?string $entityType, array $with): Action
     {
         $className = $this->getClassName($action, $entityType);
@@ -74,6 +79,9 @@ class ActionFactory
         return $this->injectableFactory->createWith($className, $with);
     }
 
+    /**
+     * @return ?class-string
+     */
     private function getClassName(string $action, ?string $entityType): ?string
     {
         if ($entityType) {
@@ -89,6 +97,9 @@ class ActionFactory
         );
     }
 
+    /**
+     * @return ?class-string
+     */
     private function getEntityTypeClassName(string $action, string $entityType): ?string
     {
         return  $this->metadata->get(
diff --git a/application/Espo/Core/Action/Actions/ConvertCurrency.php b/application/Espo/Core/Action/Actions/ConvertCurrency.php
index f40eb0fbeb..d27ced965b 100644
--- a/application/Espo/Core/Action/Actions/ConvertCurrency.php
+++ b/application/Espo/Core/Action/Actions/ConvertCurrency.php
@@ -124,6 +124,9 @@ class ConvertCurrency implements Action
         $this->convertEntity($entity, $fieldList, $targetCurrency, $rates);
     }
 
+    /**
+     * @param string[] $fieldList
+     */
     protected function convertEntity(
         Entity $entity,
         array $fieldList,
@@ -179,6 +182,9 @@ class ConvertCurrency implements Action
         return CurrencyRates::fromArray($ratesArray);
     }
 
+    /**
+     * @return string[]
+     */
     protected function getFieldList(string $entityType, Data $data): array
     {
         $forbiddenFieldList = $this->acl->getScopeForbiddenFieldList($entityType, 'edit');
diff --git a/application/Espo/Core/Action/Actions/Merge/Merger.php b/application/Espo/Core/Action/Actions/Merge/Merger.php
index 67047b52fe..308f66c217 100644
--- a/application/Espo/Core/Action/Actions/Merge/Merger.php
+++ b/application/Espo/Core/Action/Actions/Merge/Merger.php
@@ -48,17 +48,17 @@ use Espo\Entities\{
     EmailAddress,
 };
 
-use StdClass;
+use stdClass;
 
 class Merger
 {
-    private $acl;
+    private Acl $acl;
 
-    private $metadata;
+    private Metadata $metadata;
 
-    private $entityManager;
+    private EntityManager $entityManager;
 
-    private $serviceContainer;
+    private ServiceContainer $serviceContainer;
 
     public function __construct(
         Acl $acl,
@@ -73,10 +73,11 @@ class Merger
     }
 
     /**
+     * @param string[] $sourceIdList
      * @throws NotFound
      * @throws Forbidden
      */
-    public function process(Params $params, array $sourceIdList, StdClass $data): void
+    public function process(Params $params, array $sourceIdList, stdClass $data): void
     {
         $clonedData = ObjectUtil::clone($data);
 
@@ -171,6 +172,7 @@ class Merger
     }
 
     /**
+     * @param string[] $sourceIdList
      * @return Entity[]
      * @throws Forbidden
      * @throws NotFound
@@ -323,7 +325,7 @@ class Merger
     /**
      * @param PhoneNumber[] $phoneNumberList
      */
-    private function preparePhoneNumberData(array $phoneNumberList, StdClass $data): void
+    private function preparePhoneNumberData(array $phoneNumberList, stdClass $data): void
     {
         $phoneNumberData = [];
 
@@ -354,7 +356,7 @@ class Merger
     /**
      * @param EmailAddress[] $emailAddressList
      */
-    private function prepareEmailAddressData(array $emailAddressList, StdClass $data): void
+    private function prepareEmailAddressData(array $emailAddressList, stdClass $data): void
     {
         $emailAddressData = [];
 
diff --git a/application/Espo/Core/ApplicationRunners/ClearCache.php b/application/Espo/Core/ApplicationRunners/ClearCache.php
index 044123b0c4..71b4ceea58 100644
--- a/application/Espo/Core/ApplicationRunners/ClearCache.php
+++ b/application/Espo/Core/ApplicationRunners/ClearCache.php
@@ -41,7 +41,7 @@ class ClearCache implements Runner
 {
     use Cli;
 
-    protected $dataManager;
+    private DataManager $dataManager;
 
     public function __construct(DataManager $dataManager)
     {
diff --git a/application/Espo/Core/ApplicationRunners/Cli.php b/application/Espo/Core/ApplicationRunners/Cli.php
index e7ef365e3f..558efccb36 100644
--- a/application/Espo/Core/ApplicationRunners/Cli.php
+++ b/application/Espo/Core/ApplicationRunners/Cli.php
@@ -34,5 +34,5 @@ namespace Espo\Core\ApplicationRunners;
  */
 trait Cli
 {
-    public static $cli = true;
+    public static bool $cli = true;
 }
diff --git a/application/Espo/Core/ApplicationRunners/Job.php b/application/Espo/Core/ApplicationRunners/Job.php
index c796c28af7..c6bc3faea4 100644
--- a/application/Espo/Core/ApplicationRunners/Job.php
+++ b/application/Espo/Core/ApplicationRunners/Job.php
@@ -43,7 +43,7 @@ class Job implements RunnerParameterized
     use Cli;
     use SetupSystemUser;
 
-    private $jobManager;
+    private JobManager $jobManager;
 
     public function __construct(JobManager $jobManager)
     {
diff --git a/application/Espo/Core/ApplicationRunners/Preload.php b/application/Espo/Core/ApplicationRunners/Preload.php
index 937420ddc4..70d3974843 100644
--- a/application/Espo/Core/ApplicationRunners/Preload.php
+++ b/application/Espo/Core/ApplicationRunners/Preload.php
@@ -64,7 +64,7 @@ class Preload implements Runner
         echo "Files loaded: " . (string) $count . "." . PHP_EOL;
     }
 
-    protected function processException(Throwable $e)
+    protected function processException(Throwable $e): void
     {
         echo "Error occurred." . PHP_EOL;
 
diff --git a/application/Espo/Core/ApplicationRunners/SetupSystemUser.php b/application/Espo/Core/ApplicationRunners/SetupSystemUser.php
index 9f0b5d9689..a618f7870b 100644
--- a/application/Espo/Core/ApplicationRunners/SetupSystemUser.php
+++ b/application/Espo/Core/ApplicationRunners/SetupSystemUser.php
@@ -34,5 +34,5 @@ namespace Espo\Core\ApplicationRunners;
  */
 trait SetupSystemUser
 {
-    public static $setupSystemUser = true;
+    public static bool $setupSystemUser = true;
 }
diff --git a/application/Espo/Core/Cleanup/Base.php b/application/Espo/Core/Cleanup/Base.php
index ca97b0d23c..09081d93d4 100644
--- a/application/Espo/Core/Cleanup/Base.php
+++ b/application/Espo/Core/Cleanup/Base.php
@@ -32,7 +32,7 @@ namespace Espo\Core\Cleanup;
 /** @deprecated */
 abstract class Base extends \Espo\Core\Injectable
 {
-    protected function init()
+    protected function init() /** @phpstan-ignore-line */
     {
         $this->addDependency('config');
         $this->addDependency('metadata');
@@ -40,25 +40,25 @@ abstract class Base extends \Espo\Core\Injectable
         $this->addDependency('fileManager');
     }
 
-    protected function getConfig()
+    protected function getConfig() /** @phpstan-ignore-line */
     {
         return $this->getInjection('config');
     }
 
-    protected function getMetadata()
+    protected function getMetadata() /** @phpstan-ignore-line */
     {
         return $this->getInjection('metadata');
     }
 
-    protected function getEntityManager()
+    protected function getEntityManager() /** @phpstan-ignore-line */
     {
         return $this->getInjection('entityManager');
     }
 
-    protected function getFileManager()
+    protected function getFileManager() /** @phpstan-ignore-line */
     {
         return $this->getInjection('fileManager');
     }
 
-    abstract public function process();
+    abstract public function process(); /** @phpstan-ignore-line */
 }