diff --git a/application/Espo/Core/Authentication/Oidc/KeysProvider.php b/application/Espo/Core/Authentication/Oidc/KeysProvider.php
index 0116f46c4a..e05b10bf6a 100644
--- a/application/Espo/Core/Authentication/Oidc/KeysProvider.php
+++ b/application/Espo/Core/Authentication/Oidc/KeysProvider.php
@@ -128,7 +128,7 @@ class KeysProvider
         /** @var string|false $response */
         $response = curl_exec($curl);
         $error = curl_error($curl);
-        $status = curl_getinfo($curl, CURLINFO_HTTP_CODE) ?? 0;
+        $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
 
         curl_close($curl);
 
diff --git a/application/Espo/Core/Authentication/Oidc/Login.php b/application/Espo/Core/Authentication/Oidc/Login.php
index 3bbe451e52..e592b65e7c 100644
--- a/application/Espo/Core/Authentication/Oidc/Login.php
+++ b/application/Espo/Core/Authentication/Oidc/Login.php
@@ -226,7 +226,7 @@ class Login implements LoginInterface
         /** @var string|false $response */
         $response = curl_exec($curl);
         $error = curl_error($curl);
-        $status = curl_getinfo($curl, CURLINFO_HTTP_CODE) ?? 0;
+        $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
 
         curl_close($curl);
 
diff --git a/application/Espo/Core/Currency/CalculatorUtil.php b/application/Espo/Core/Currency/CalculatorUtil.php
index 0080b72b4b..3b85507fe3 100644
--- a/application/Espo/Core/Currency/CalculatorUtil.php
+++ b/application/Espo/Core/Currency/CalculatorUtil.php
@@ -88,6 +88,7 @@ class CalculatorUtil
             );
         }
 
+        /** @var ?string $result */
         $result = bcdiv(
             $arg1,
             $arg2,
diff --git a/application/Espo/Core/ExternalAccount/OAuth2/Client.php b/application/Espo/Core/ExternalAccount/OAuth2/Client.php
index 53a3aed600..244257982a 100644
--- a/application/Espo/Core/ExternalAccount/OAuth2/Client.php
+++ b/application/Espo/Core/ExternalAccount/OAuth2/Client.php
@@ -216,7 +216,7 @@ class Client
      * @return array{
      *   result: array<string,mixed>|string,
      *   code: int,
-     *   contentType: string,
+     *   contentType: string|false,
      *   header: string,
      * }
      * @throws Exception
@@ -258,9 +258,9 @@ class Client
      * @param string $httpMethod
      * @param array<string,string> $httpHeaders
      * @return array{
-     *   result: array<string,mixed>|string,
+     *   result: array<string, mixed>|string,
      *   code: int,
-     *   contentType: string,
+     *   contentType: string|false,
      *   header: string,
      * }
      * @throws Exception
@@ -353,25 +353,27 @@ class Client
         $contentType = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);
         $headerSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
 
-        $responceHeader = substr($response, 0, $headerSize);
-        $responceBody = substr($response, $headerSize);
-
-        $resultArray = null;
+        $responseHeader = substr($response, 0, $headerSize);
+        $responseBody = substr($response, $headerSize);
 
         if ($curlError = curl_error($ch)) {
             throw new Exception($curlError);
         }
-        else {
-            $resultArray = json_decode($responceBody, true);
-        }
+
+        $resultArray = json_decode($responseBody, true);
 
         curl_close($ch);
 
+        /** @var array<string, mixed>|string $result */
+        $result = ($resultArray !== null) ?
+            $resultArray :
+            $responseBody;
+
         return [
-            'result' => (null !== $resultArray) ? $resultArray : $responceBody,
+            'result' => $result,
             'code' => intval($httpCode),
             'contentType' => $contentType,
-            'header' => $responceHeader,
+            'header' => $responseHeader,
         ];
     }
 
@@ -383,9 +385,9 @@ class Client
      *   client_secret?: string,
      * } $params
      * @return array{
-     *   result: array<string,mixed>|string,
+     *   result: array<string, mixed>|string,
      *   code: int,
-     *   contentType: string,
+     *   contentType: string|false,
      *   header: string,
      * }
      * @throws Exception
diff --git a/application/Espo/Core/Formula/Functions/EntityGroup/CountRelatedType.php b/application/Espo/Core/Formula/Functions/EntityGroup/CountRelatedType.php
index f168512baa..66cbb31e38 100644
--- a/application/Espo/Core/Formula/Functions/EntityGroup/CountRelatedType.php
+++ b/application/Espo/Core/Formula/Functions/EntityGroup/CountRelatedType.php
@@ -31,7 +31,7 @@ namespace Espo\Core\Formula\Functions\EntityGroup;
 
 use Espo\Core\Exceptions\Error;
 
-use Espo\Core\ORM\EntityManager;
+use Espo\ORM\EntityManager;
 
 use Espo\Core\Di;
 
diff --git a/application/Espo/Core/Formula/Functions/EntityGroup/GetLinkColumnType.php b/application/Espo/Core/Formula/Functions/EntityGroup/GetLinkColumnType.php
index 12734330d4..ec43554f98 100644
--- a/application/Espo/Core/Formula/Functions/EntityGroup/GetLinkColumnType.php
+++ b/application/Espo/Core/Formula/Functions/EntityGroup/GetLinkColumnType.php
@@ -31,7 +31,7 @@ namespace Espo\Core\Formula\Functions\EntityGroup;
 
 use Espo\Core\Exceptions\Error;
 
-use Espo\Core\ORM\EntityManager;
+use Espo\ORM\EntityManager;
 
 use Espo\Core\Di;
 
diff --git a/application/Espo/Core/Formula/Functions/EntityGroup/IsRelatedType.php b/application/Espo/Core/Formula/Functions/EntityGroup/IsRelatedType.php
index 065b9f197e..df37bdf63e 100644
--- a/application/Espo/Core/Formula/Functions/EntityGroup/IsRelatedType.php
+++ b/application/Espo/Core/Formula/Functions/EntityGroup/IsRelatedType.php
@@ -31,7 +31,7 @@ namespace Espo\Core\Formula\Functions\EntityGroup;
 
 use Espo\Core\Exceptions\Error;
 
-use Espo\Core\ORM\EntityManager;
+use Espo\ORM\EntityManager;
 
 use Espo\Core\Di;
 
diff --git a/application/Espo/Core/Formula/Functions/RecordGroup/ExistsType.php b/application/Espo/Core/Formula/Functions/RecordGroup/ExistsType.php
index 3d205c7fc8..f59ab05ce5 100644
--- a/application/Espo/Core/Formula/Functions/RecordGroup/ExistsType.php
+++ b/application/Espo/Core/Formula/Functions/RecordGroup/ExistsType.php
@@ -29,7 +29,7 @@
 
 namespace Espo\Core\Formula\Functions\RecordGroup;
 
-use Espo\Core\ORM\EntityManager;
+use Espo\ORM\EntityManager;
 
 use Espo\Core\Formula\{
     Functions\BaseFunction,
diff --git a/application/Espo/Core/Log/Handler/EspoRotatingFileHandler.php b/application/Espo/Core/Log/Handler/EspoRotatingFileHandler.php
index 22a9fba27d..2780bc34dd 100644
--- a/application/Espo/Core/Log/Handler/EspoRotatingFileHandler.php
+++ b/application/Espo/Core/Log/Handler/EspoRotatingFileHandler.php
@@ -105,13 +105,13 @@ class EspoRotatingFileHandler extends EspoFileHandler
         $fileInfo = pathinfo($this->filename);
 
         $timedFilename = str_replace(
-            array('{filename}', '{date}'),
-            array($fileInfo['filename'], date($this->dateFormat)),
-            $fileInfo['dirname'] . '/' . $this->filenameFormat
+            ['{filename}', '{date}'],
+            [$fileInfo['filename'], date($this->dateFormat)],
+            ($fileInfo['dirname'] ?? '') . '/' . $this->filenameFormat
         );
 
         if (!empty($fileInfo['extension'])) {
-            $timedFilename .= '.'.$fileInfo['extension'];
+            $timedFilename .= '.' . $fileInfo['extension'];
         }
 
         return $timedFilename;
diff --git a/application/Espo/Core/Mail/Parsers/MailMimeParser.php b/application/Espo/Core/Mail/Parsers/MailMimeParser.php
index c299a127e4..be242843d1 100644
--- a/application/Espo/Core/Mail/Parsers/MailMimeParser.php
+++ b/application/Espo/Core/Mail/Parsers/MailMimeParser.php
@@ -66,7 +66,6 @@ class MailMimeParser implements Parser
     ];
 
     private EntityManager $entityManager;
-
     private ?WrappeeParser $parser = null;
 
     /**
@@ -337,11 +336,12 @@ class MailMimeParser implements Parser
                 $contentId = trim($contentId, '<>');
             }
 
-            if ($disposition == 'inline') {
+            if ($disposition === 'inline') {
                 $attachment->set('role', Attachment::ROLE_INLINE_ATTACHMENT);
             }
             else {
                 $disposition = 'attachment';
+
                 $attachment->set('role', Attachment::ROLE_ATTACHMENT);
             }
 
@@ -349,23 +349,27 @@ class MailMimeParser implements Parser
 
             $this->entityManager->saveEntity($attachment);
 
-            if ($disposition == 'attachment') {
+            if ($disposition === 'attachment') {
                 $email->addLinkMultipleId('attachments', $attachment->getId());
 
                 if ($contentId) {
                     $inlineIds[$contentId] = $attachment->getId();
                 }
-            }
-            else if ($disposition == 'inline') {
-                if ($contentId) {
-                    $inlineIds[$contentId] = $attachment->getId();
 
-                    $inlineAttachmentList[] = $attachment;
-                }
-                else {
-                    $email->addLinkMultipleId('attachments', $attachment->getId());
-                }
+                continue;
             }
+
+            // inline
+
+            if ($contentId) {
+                $inlineIds[$contentId] = $attachment->getId();
+
+                $inlineAttachmentList[] = $attachment;
+
+                continue;
+            }
+
+            $email->addLinkMultipleId('attachments', $attachment->getId());
         }
 
         $body = $email->get('body');
diff --git a/application/Espo/Core/Utils/DataUtil.php b/application/Espo/Core/Utils/DataUtil.php
index 86bbb5bba2..81b08c4e99 100644
--- a/application/Espo/Core/Utils/DataUtil.php
+++ b/application/Espo/Core/Utils/DataUtil.php
@@ -31,6 +31,7 @@ namespace Espo\Core\Utils;
 
 use InvalidArgumentException;
 use LogicException;
+use stdClass;
 
 class DataUtil
 {
@@ -114,9 +115,9 @@ class DataUtil
     }
 
     /**
-     * @param array<string|int,mixed>|\stdClass $data
+     * @param array<string|int,mixed>|stdClass $data
      * @param mixed $needle
-     * @return array<string|int,mixed>|\stdClass
+     * @return array<string|int,mixed>|stdClass
      */
     public static function unsetByValue(&$data, $needle)
     {
@@ -150,25 +151,25 @@ class DataUtil
     }
 
     /**
-     *
-     * @param array<string,mixed>|\stdClass $data
-     * @param array<string,mixed>|\stdClass $overrideData
-     * @return array<string|int,mixed>|\stdClass
+     * @param array<string, mixed>|stdClass $data
+     * @param array<string, mixed>|stdClass $overrideData
+     * @return array<string|int, mixed>|stdClass
      */
     public static function merge($data, $overrideData)
     {
         $appendIdentifier = '__APPEND__';
 
+        if (
+            is_object($data) &&
+            is_object($overrideData) &&
+            get_object_vars($data) === [] &&
+            get_object_vars($overrideData) === []
+        ) {
+            return (object) [];
+        }
+
         if (empty($data) && empty($overrideData)) {
-            if (is_object($data) || is_object($overrideData)) {
-                return (object) [];
-            }
-            else if (is_array($data) || is_array($overrideData)) {
-                return [];
-            }
-            else {
-                return $overrideData;
-            }
+            return [];
         }
 
         if (is_object($overrideData)) {
@@ -188,7 +189,8 @@ class DataUtil
 
             return $data;
         }
-        else if (is_array($overrideData)) {
+
+        if (is_array($overrideData)) {
             if (empty($data)) {
                 $data = [];
             }
@@ -203,15 +205,13 @@ class DataUtil
 
                     $data[] = $item;
                 }
-            }
-            else {
-                $data = $overrideData;
+
+                return $data;
             }
 
-            return $data;
-        }
-        else {
             return $overrideData;
         }
+
+        return $overrideData;
     }
 }
diff --git a/application/Espo/Core/Utils/Database/Orm/Relations/Base.php b/application/Espo/Core/Utils/Database/Orm/Relations/Base.php
index 3284dab403..bf5d1960e7 100644
--- a/application/Espo/Core/Utils/Database/Orm/Relations/Base.php
+++ b/application/Espo/Core/Utils/Database/Orm/Relations/Base.php
@@ -205,7 +205,7 @@ class Base extends \Espo\Core\Utils\Database\Orm\Base
 
     /**
      * @param string $allowedItemName
-     * @return ?array<string,mixed>'
+     * @return ?array<string,mixed>
      */
     private function getAllowedAdditionalParam($allowedItemName)
     {
@@ -219,20 +219,23 @@ class Base extends \Espo\Core\Utils\Database\Orm\Base
 
         $additionalParam = null;
 
-        $linkName = $this->getLinkName();
-        $entityName = $this->getEntityName();
-
         if (isset($itemLinkParams) && isset($itemForeignLinkParams)) {
             if (!empty($itemLinkParams) && !is_array($itemLinkParams)) {
                 $additionalParam = $itemLinkParams;
-            } else if (!empty($itemForeignLinkParams) && !is_array($itemForeignLinkParams)) {
+            }
+            else if (!empty($itemForeignLinkParams) && !is_array($itemForeignLinkParams)) {
                 $additionalParam = $itemForeignLinkParams;
-            } else {
+            }
+            else {
+                /** @var array<int|string, mixed> $itemLinkParams */
+                /** @var array<int|string, mixed> $itemForeignLinkParams */
                 $additionalParam = Util::merge($itemLinkParams, $itemForeignLinkParams);
             }
-        } else if (isset($itemLinkParams)) {
+        }
+        else if (isset($itemLinkParams)) {
             $additionalParam = $itemLinkParams;
-        } else if (isset($itemForeignLinkParams)) {
+        }
+        else if (isset($itemForeignLinkParams)) {
             $additionalParam = $itemForeignLinkParams;
         }
 
diff --git a/application/Espo/Core/Utils/File/Manager.php b/application/Espo/Core/Utils/File/Manager.php
index 8a4a0efd16..76952c737f 100644
--- a/application/Espo/Core/Utils/File/Manager.php
+++ b/application/Espo/Core/Utils/File/Manager.php
@@ -55,11 +55,8 @@ class Manager
     protected string $tmpDir = 'data/tmp';
 
     protected const RENAME_RETRY_NUMBER = 10;
-
     protected const RENAME_RETRY_INTERVAL = 0.1;
-
     protected const GET_SAFE_CONTENTS_RETRY_NUMBER = 10;
-
     protected const GET_SAFE_CONTENTS_RETRY_INTERVAL = 0.1;
 
     /**
@@ -127,41 +124,49 @@ class Manager
 
         $cdir = scandir($path) ?: [];
 
-        foreach ($cdir as $key => $value) {
-            if (!in_array($value, [".", ".."])) {
-                $add = false;
+        foreach ($cdir as $value) {
+            if (in_array($value, [".", ".."])) {
+                continue;
+            }
 
-                if (is_dir($path . Util::getSeparator() . $value)) {
-                    if ($recursively || (is_int($recursively) && $recursively!=0)) {
-                        $nextRecursively = is_int($recursively) ? ($recursively-1) : $recursively;
+            $add = false;
 
-                        $result[$value] = $this->getFileList(
-                            $path . Util::getSeparator() . $value,
-                            $nextRecursively,
-                            $filter,
-                            $onlyFileType
-                        );
-                    }
-                    else if (!isset($onlyFileType) || !$onlyFileType){ /*save only directories*/
-                        $add = true;
-                    }
+            if (is_dir($path . Util::getSeparator() . $value)) {
+                /** @var mixed $recursively */
+                if (
+                    !is_int($recursively) && $recursively ||
+                    is_int($recursively) && $recursively !== 0
+                ) {
+                    $nextRecursively = is_int($recursively) ? ($recursively - 1) : $recursively;
+
+                    $result[$value] = $this->getFileList(
+                        $path . Util::getSeparator() . $value,
+                        $nextRecursively,
+                        $filter,
+                        $onlyFileType
+                    );
                 }
-                else if (!isset($onlyFileType) || $onlyFileType) { /*save only files*/
+                else if (!isset($onlyFileType) || !$onlyFileType) { /* save only directories */
                     $add = true;
                 }
+            }
+            else if (!isset($onlyFileType) || $onlyFileType) { /* save only files */
+                $add = true;
+            }
 
-                if ($add) {
-                    if (!empty($filter)) {
-                        if (preg_match('/'.$filter.'/i', $value)) {
-                            $result[] = $value;
-                        }
-                    }
-                    else {
-                        $result[] = $value;
-                    }
+            if (!$add) {
+                continue;
+            }
+
+            if (!empty($filter)) {
+                if (preg_match('/'.$filter.'/i', $value)) {
+                    $result[] = $value;
                 }
 
+                continue;
             }
+
+            $result[] = $value;
         }
 
         if ($returnSingleArray) {
@@ -677,17 +682,18 @@ class Manager
 
         $pathParts = pathinfo($filePath);
 
-        if (!file_exists($pathParts['dirname'])) {
+        /** @var string $dirname */
+        $dirname = $pathParts['dirname'] ?? null;
+
+        if (!file_exists($dirname)) {
             $dirPermissionOriginal = $defaultPermissions['dir'];
 
             $dirPermission = is_string($dirPermissionOriginal) ?
                 (int) base_convert($dirPermissionOriginal, 8, 10) :
                 $dirPermissionOriginal;
 
-            if (!$this->mkdir($pathParts['dirname'], $dirPermission)) {
-                throw new PermissionError(
-                    'Permission denied: unable to create a folder on the server ' . $pathParts['dirname']
-                );
+            if (!$this->mkdir($dirname, $dirPermission)) {
+                throw new PermissionError('Permission denied: unable to create a folder on the server ' . $dirname);
             }
         }
 
diff --git a/application/Espo/Core/Utils/File/Permission.php b/application/Espo/Core/Utils/File/Permission.php
index 97a07214cb..888502f6a0 100644
--- a/application/Espo/Core/Utils/File/Permission.php
+++ b/application/Espo/Core/Utils/File/Permission.php
@@ -591,7 +591,8 @@ class Permission
 
         foreach ($fileList as $fileName) {
             $pathInfo = pathinfo($fileName);
-            $dirname = $pathInfo['dirname'];
+            /** @var string $dirname */
+            $dirname = $pathInfo['dirname'] ?? null;
 
             $currentPath = $fileName;
 
diff --git a/application/Espo/Core/Utils/Language.php b/application/Espo/Core/Utils/Language.php
index 8c60060e90..0d67f1e796 100644
--- a/application/Espo/Core/Utils/Language.php
+++ b/application/Espo/Core/Utils/Language.php
@@ -398,7 +398,7 @@ class Language
     private function getLanguageData(string $language, bool $reload = false): array
     {
         if (!$reload && isset($this->data[$language])) {
-            return $this->data[$language] ?? [];
+            return $this->data[$language];
         }
 
         $cacheKey = $this->getCacheKey($language);