diff --git a/application/Espo/Core/Utils/Database/Converter.php b/application/Espo/Core/Utils/Database/Converter.php
index fe8b853948..e73dfdec90 100644
--- a/application/Espo/Core/Utils/Database/Converter.php
+++ b/application/Espo/Core/Utils/Database/Converter.php
@@ -43,9 +43,9 @@ class Converter
 
     private $config;
 
-    private $ormConverter;
+    private Orm\Converter $ormConverter;
 
-    public function __construct(Metadata $metadata, FileManager $fileManager, Config $config = null)
+    public function __construct(Metadata $metadata, FileManager $fileManager, ?Config $config = null)
     {
         $this->metadata = $metadata;
         $this->fileManager = $fileManager;
@@ -53,16 +53,19 @@ class Converter
         $this->ormConverter = new Orm\Converter($this->metadata, $this->fileManager, $this->config);
     }
 
-    protected function getMetadata()
+    protected function getMetadata(): Metadata
     {
         return $this->metadata;
     }
 
-    protected function getOrmConverter()
+    protected function getOrmConverter(): Orm\Converter
     {
         return $this->ormConverter;
     }
 
+    /**
+     * @return array<string,mixed>
+     */
     public function process()
     {
         $data = $this->getOrmConverter()->process();
diff --git a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/BoolType.php b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/BoolType.php
index a255573ac6..9fefff7274 100644
--- a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/BoolType.php
+++ b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/BoolType.php
@@ -35,11 +35,17 @@ class BoolType extends BooleanType
 {
     const BOOL = 'bool';
 
+    /**
+     * @return string
+     */
     public function getName()
     {
         return self::BOOL;
     }
 
+    /**
+     * @return string
+     */
     public static function getDbTypeName()
     {
         return 'TINYINT';
diff --git a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/PasswordType.php b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/PasswordType.php
index 92656c8d1c..57c9e8f85a 100644
--- a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/PasswordType.php
+++ b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/PasswordType.php
@@ -35,14 +35,19 @@ class PasswordType extends StringType
 {
     const PASSWORD = 'password';
 
+    /**
+     * @return string
+     */
     public function getName()
     {
         return self::PASSWORD;
     }
 
+    /**
+     * @return string
+     */
     public static function getDbTypeName()
     {
         return 'VARCHAR';
     }
 }
-
diff --git a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/TextType.php b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/TextType.php
index 032fca2508..9dc1163cd5 100644
--- a/application/Espo/Core/Utils/Database/DBAL/FieldTypes/TextType.php
+++ b/application/Espo/Core/Utils/Database/DBAL/FieldTypes/TextType.php
@@ -33,11 +33,18 @@ use Doctrine\DBAL\Platforms\AbstractPlatform;
 
 class TextType extends \Doctrine\DBAL\Types\TextType
 {
+    /**
+     * @return string
+     */
     public static function getDbTypeName()
     {
         return 'mediumtext';
     }
 
+    /**
+     * @param array<string,mixed> $fieldDeclaration
+     * @return string
+     */
     public function getSQLDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
     {
         return 'MEDIUMTEXT';
diff --git a/application/Espo/Core/Utils/Database/DBAL/Traits/Schema/Comparator.php b/application/Espo/Core/Utils/Database/DBAL/Traits/Schema/Comparator.php
index ea837ebf63..94aba09171 100644
--- a/application/Espo/Core/Utils/Database/DBAL/Traits/Schema/Comparator.php
+++ b/application/Espo/Core/Utils/Database/DBAL/Traits/Schema/Comparator.php
@@ -36,8 +36,11 @@ use Doctrine\DBAL\{
 
 trait Comparator
 {
-    /*
+    /**
      * Fix problem with executing query for custom types
+     *
+     * @param string[] $changedProperties
+     * @return void
      */
     protected function espoFixTypeDiff(array &$changedProperties, Column $column1, Column $column2)
     {
@@ -60,8 +63,10 @@ trait Comparator
             $changedProperties[] = 'type';
         }
     }
-    /* Espo: end */
 
+    /**
+     * @return string
+     */
     private function getColumnDbType(Column $column)
     {
         $dbType = $column->getType()->getName();
@@ -73,6 +78,9 @@ trait Comparator
         return strtoupper($dbType);
     }
 
+    /**
+     * @return ?int
+     */
     private function getColumnDbLength(Column $column)
     {
         $dbType = $this->getColumnDbType($column);
@@ -87,5 +95,7 @@ trait Comparator
         if (defined($constName)) {
             return constant($constName);
         }
+
+        return null;
     }
 }