diff --git a/application/Espo/Controllers/EmailAddress.php b/application/Espo/Controllers/EmailAddress.php
index e39a2aff2b..c8e365fe4a 100644
--- a/application/Espo/Controllers/EmailAddress.php
+++ b/application/Espo/Controllers/EmailAddress.php
@@ -30,6 +30,7 @@
 namespace Espo\Controllers;
 
 use Espo\Core\Exceptions\Forbidden;
+use Espo\Core\Exceptions\BadRequest;
 
 use Espo\Services\EmailAddress as Service;
 
@@ -55,6 +56,10 @@ class EmailAddress extends RecordBase
 
         $q = $request->getQueryParam('q');
 
+        if ($q === null) {
+            throw new BadRequest("No `q` parameter.");
+        }
+
         $maxSize = intval($request->getQueryParam('maxSize'));
 
         if (empty($maxSize) || $maxSize > 50) {
diff --git a/application/Espo/Controllers/EmailTemplate.php b/application/Espo/Controllers/EmailTemplate.php
index 59060881cb..3fe45ca359 100644
--- a/application/Espo/Controllers/EmailTemplate.php
+++ b/application/Espo/Controllers/EmailTemplate.php
@@ -29,6 +29,8 @@
 
 namespace Espo\Controllers;
 
+use Espo\Core\Exceptions\BadRequest;
+
 use Espo\Services\EmailTemplate as Service;
 
 use Espo\Core\{
@@ -44,6 +46,10 @@ class EmailTemplate extends Record
     {
         $id = $request->getQueryParam('id');
 
+        if ($id === null) {
+            throw new BadRequest("No `id`.");
+        }
+
         return (object) $this->getEmailTempalteService()->parse(
             $id,
             [
diff --git a/application/Espo/Controllers/Export.php b/application/Espo/Controllers/Export.php
index b1702dfa0e..4e93cebca4 100644
--- a/application/Espo/Controllers/Export.php
+++ b/application/Espo/Controllers/Export.php
@@ -62,8 +62,12 @@ class Export
         $result = $this->service->process($params, $serviceParams);
 
         if ($result->hasResult()) {
+            $subResult = $result->getResult();
+
+            assert($subResult !== null);
+
             return (object) [
-                'id' => $result->getResult()->getAttachmentId(),
+                'id' => $subResult->getAttachmentId(),
             ];
         }
 
diff --git a/application/Espo/Controllers/Extension.php b/application/Espo/Controllers/Extension.php
index 15fd37e7bd..3785630f71 100644
--- a/application/Espo/Controllers/Extension.php
+++ b/application/Espo/Controllers/Extension.php
@@ -30,6 +30,7 @@
 namespace Espo\Controllers;
 
 use Espo\Core\Exceptions\Forbidden;
+use Espo\Core\Exceptions\BadRequest;
 
 use Espo\Core\{
     Upgrades\ExtensionManager,
@@ -51,6 +52,10 @@ class Extension extends RecordBase
     {
         $body = $request->getBodyContents();
 
+        if ($body === null) {
+            throw new BadRequest();
+        }
+
         $manager = new ExtensionManager($this->getContainer());
 
         $id = $manager->upload($body);
diff --git a/application/Espo/Controllers/ExternalAccount.php b/application/Espo/Controllers/ExternalAccount.php
index 928a383701..3fddd2c2ae 100644
--- a/application/Espo/Controllers/ExternalAccount.php
+++ b/application/Espo/Controllers/ExternalAccount.php
@@ -30,6 +30,8 @@
 namespace Espo\Controllers;
 
 use Espo\Core\Exceptions\Forbidden;
+use Espo\Core\Exceptions\BadRequest;
+use Espo\Core\Exceptions\NotFound;
 
 use Espo\Services\ExternalAccount as Service;
 
@@ -91,6 +93,10 @@ class ExternalAccount extends RecordBase
     {
         $id = $request->getQueryParam('id');
 
+        if ($id === null) {
+            throw new BadRequest();
+        }
+
         list($integration, $userId) = explode('__', $id);
 
         if ($this->user->getId() != $userId && !$this->user->isAdmin()) {
@@ -112,6 +118,7 @@ class ExternalAccount extends RecordBase
 
     public function getActionRead(Request $request, Response $response): stdClass
     {
+        /** @var string */
         $id = $request->getRouteParam('id');
 
         return $this->getRecordService()
@@ -121,11 +128,12 @@ class ExternalAccount extends RecordBase
 
     public function putActionUpdate(Request $request, Response $response): stdClass
     {
+        /** @var string */
         $id = $request->getRouteParam('id');
 
         $data = $request->getParsedBody();
 
-        list ($integration, $userId) = explode('__', $id);
+        list($integration, $userId) = explode('__', $id);
 
         if ($this->user->getId() !== $userId && !$this->user->isAdmin()) {
             throw new Forbidden();
@@ -137,6 +145,10 @@ class ExternalAccount extends RecordBase
 
         $entity = $this->entityManager->getEntity('ExternalAccount', $id);
 
+        if (!$entity) {
+            throw new NotFound();
+        }
+
         $entity->set($data);
 
         $this->entityManager->saveEntity($entity);
diff --git a/application/Espo/Controllers/GlobalSearch.php b/application/Espo/Controllers/GlobalSearch.php
index 0ff89fb871..19110ee682 100644
--- a/application/Espo/Controllers/GlobalSearch.php
+++ b/application/Espo/Controllers/GlobalSearch.php
@@ -29,8 +29,8 @@
 
 namespace Espo\Controllers;
 
+use Espo\Core\Exceptions\BadRequest;
 use Espo\Services\GlobalSearch as Service;
-
 use Espo\Core\Api\Request;
 
 use stdClass;
@@ -48,6 +48,10 @@ class GlobalSearch
     {
         $query = $request->getQueryParam('q');
 
+        if ($query === null) {
+            throw new BadRequest("No `q` parameter.");
+        }
+
         $offset = intval($request->getQueryParam('offset'));
         $maxSize = intval($request->getQueryParam('maxSize'));
 
diff --git a/application/Espo/Controllers/Import.php b/application/Espo/Controllers/Import.php
index 623fbea63e..2192c6bcb2 100644
--- a/application/Espo/Controllers/Import.php
+++ b/application/Espo/Controllers/Import.php
@@ -64,7 +64,7 @@ class Import extends Record
 
     public function postActionUploadFile(Request $request): stdClass
     {
-        $contents = $request->getBodyContents();
+        $contents = $request->getBodyContents() ?? '';
 
         $attachmentId = $this->getImportService()->uploadFile($contents);
 
diff --git a/application/Espo/Controllers/Integration.php b/application/Espo/Controllers/Integration.php
index f16ae4517c..0131c5b932 100644
--- a/application/Espo/Controllers/Integration.php
+++ b/application/Espo/Controllers/Integration.php
@@ -56,14 +56,21 @@ class Integration
 
     public function getActionRead(Request $request): stdClass
     {
-        $entity = $this->service->read($request->getRouteParam('id'));
+        /** @var string */
+        $id = $request->getRouteParam('id');
+
+        $entity = $this->service->read($id);
 
         return $entity->getValueMap();
     }
 
     public function putActionUpdate(Request $request): stdClass
     {
-        $entity = $this->service->update($request->getRouteParam('id'), $request->getParsedBody());
+        /** @var string */
+        $id = $request->getRouteParam('id');
+        $data = $request->getParsedBody();
+
+        $entity = $this->service->update($id, $data);
 
         return $entity->getValueMap();
     }
diff --git a/application/Espo/Controllers/Kanban.php b/application/Espo/Controllers/Kanban.php
index 3332c4e215..bed7da86d5 100644
--- a/application/Espo/Controllers/Kanban.php
+++ b/application/Espo/Controllers/Kanban.php
@@ -37,7 +37,7 @@ use Espo\Core\{
 
 use Espo\Tools\Kanban\KanbanService;
 
-use StdClass;
+use stdClass;
 
 class Kanban
 {
@@ -51,8 +51,9 @@ class Kanban
         $this->searchParamsFetcher = $searchParamsFetcher;
     }
 
-    public function getActionGetData(Request $request): StdClass
+    public function getActionGetData(Request $request): stdClass
     {
+        /** @var string */
         $entityType = $request->getRouteParam('entityType');
 
         $searchParams = $this->searchParamsFetcher->fetch($request);
diff --git a/application/Espo/Controllers/Layout.php b/application/Espo/Controllers/Layout.php
index 6fd8f9505a..4b42c35e51 100644
--- a/application/Espo/Controllers/Layout.php
+++ b/application/Espo/Controllers/Layout.php
@@ -31,10 +31,9 @@ namespace Espo\Controllers;
 
 use Espo\Core\Exceptions\Forbidden;
 use Espo\Core\Exceptions\BadRequest;
+
 use Espo\Core\Api\Request;
-
 use Espo\Services\Layout as Service;
-
 use Espo\Entities\User;
 
 class Layout
@@ -59,6 +58,10 @@ class Layout
         $scope = $params['scope'] ?? null;
         $name = $params['name'] ?? null;
 
+        if (!$scope || !$name) {
+            throw new BadRequest();
+        }
+
         return $this->service->getForFrontend($scope, $name);
     }
 
@@ -69,7 +72,7 @@ class Layout
     {
         $params = $request->getRouteParams();
 
-        $data = json_decode($request->getBodyContents());
+        $data = json_decode($request->getBodyContents() ?? 'null');
 
         if (is_object($data)) {
             $data = get_object_vars($data);
@@ -83,6 +86,10 @@ class Layout
         $name = $params['name'] ?? null;
         $setId = $params['setId'] ?? null;
 
+        if (!$scope || !$name) {
+            throw new BadRequest();
+        }
+
         return $this->service->update($scope, $name, $setId, $data);
     }
 
@@ -113,10 +120,14 @@ class Layout
             throw new Forbidden();
         }
 
-        return $this->service->getOriginal(
-            $request->getQueryParam('scope'),
-            $request->getQueryParam('name'),
-            $request->getQueryParam('setId')
-        );
+        $scope = $request->getQueryParam('scope');
+        $name = $request->getQueryParam('name');
+        $setId = $request->getQueryParam('setId');
+
+        if (!$scope || !$name) {
+            throw new BadRequest("No `scope` or `name` parameter.");
+        }
+
+        return $this->service->getOriginal($scope, $name, $setId);
     }
 }
diff --git a/application/Espo/Entities/Email.php b/application/Espo/Entities/Email.php
index 14da8265b0..0b5673eb86 100644
--- a/application/Espo/Entities/Email.php
+++ b/application/Espo/Entities/Email.php
@@ -40,6 +40,8 @@ use Espo\Repositories\Email as EmailRepository;
 use Espo\Core\Field\LinkParent;
 use Espo\Core\Field\Link;
 
+use RuntimeException;
+
 class Email extends Entity
 {
     public const ENTITY_TYPE = 'Email';
@@ -178,6 +180,10 @@ class Email extends Entity
         $attachment->set('parentId', $this->id);
         $attachment->set('parentType', 'Email');
 
+        if (!$this->entityManager) {
+            throw new RuntimeException();
+        }
+
         $this->entityManager->saveEntity($attachment);
     }
 
@@ -301,6 +307,10 @@ class Email extends Entity
 
             $idList[] = $id;
 
+            if (!$this->entityManager) {
+                throw new RuntimeException();
+            }
+
             /** @var Attachment|null */
             $attachment = $this->entityManager->getEntity('Attachment', $id);
 
@@ -531,6 +541,10 @@ class Email extends Entity
 
     private function getEmailRepository(): EmailRepository
     {
+        if (!$this->entityManager) {
+            throw new RuntimeException();
+        }
+
         /** @var EmailRepository */
         return $this->entityManager->getRepository(self::ENTITY_TYPE);
     }
diff --git a/application/Espo/Entities/Note.php b/application/Espo/Entities/Note.php
index d1d9e321a4..35180d8880 100644
--- a/application/Espo/Entities/Note.php
+++ b/application/Espo/Entities/Note.php
@@ -33,6 +33,7 @@ use Espo\Core\ORM\Entity;
 
 use Espo\Core\Field\DateTime;
 
+use RuntimeException;
 use stdClass;
 
 class Note extends Entity
@@ -145,6 +146,10 @@ class Note extends Entity
             return;
         }
 
+        if (!$this->entityManager) {
+            throw new RuntimeException();
+        }
+
         $attachmentsIds = $data->attachmentsIds;
 
         $collection = $this->entityManager
diff --git a/application/Espo/Entities/Sms.php b/application/Espo/Entities/Sms.php
index 2228fe6fa4..b17c6a74d5 100644
--- a/application/Espo/Entities/Sms.php
+++ b/application/Espo/Entities/Sms.php
@@ -35,6 +35,8 @@ use Espo\Core\Field\DateTime;
 
 use Espo\Repositories\Sms as SmsRepository;
 
+use RuntimeException;
+
 class Sms extends Entity implements SmsInterface
 {
     public const ENTITY_TYPE = 'Sms';
@@ -148,6 +150,10 @@ class Sms extends Entity implements SmsInterface
 
     private function getSmsRepository(): SmsRepository
     {
+        if (!$this->entityManager) {
+            throw new RuntimeException();
+        }
+
         /** @var SmsRepository */
         return $this->entityManager->getRepository(self::ENTITY_TYPE);
     }
diff --git a/application/Espo/Entities/User.php b/application/Espo/Entities/User.php
index 0a11c9ac89..9799309de7 100644
--- a/application/Espo/Entities/User.php
+++ b/application/Espo/Entities/User.php
@@ -122,6 +122,7 @@ class User extends Person
      */
     public function getTeamIdList(): array
     {
+        /** @var string[] */
         return $this->getLinkMultipleIdList('teams');
     }
 
diff --git a/application/Espo/Modules/Crm/Business/Event/Ics.php b/application/Espo/Modules/Crm/Business/Event/Ics.php
index 053e772f8f..b4188d1a7c 100644
--- a/application/Espo/Modules/Crm/Business/Event/Ics.php
+++ b/application/Espo/Modules/Crm/Business/Event/Ics.php
@@ -80,6 +80,7 @@ class Ics
             $this->generate();
         }
 
+        /** @var string */
         return $this->output;
     }
 
@@ -119,6 +120,7 @@ class Ics
             return '';
         }
 
+        /** @var string */
         return preg_replace('/([\,;])/', '\\\$1', $string);
     }
 
diff --git a/application/Espo/Modules/Crm/Business/Event/Invitations.php b/application/Espo/Modules/Crm/Business/Event/Invitations.php
index 3b2c681968..e77ea9e6bb 100644
--- a/application/Espo/Modules/Crm/Business/Event/Invitations.php
+++ b/application/Espo/Modules/Crm/Business/Event/Invitations.php
@@ -103,7 +103,7 @@ class Invitations
 
     public function sendInvitation(Entity $entity, Entity $invitee, string $link): void
     {
-        $uid = $this->entityManager->getEntity('UniqueId');
+        $uid = $this->entityManager->getNewEntity('UniqueId');
 
         $uid->set('data', [
             'eventType' => $entity->getEntityType(),
@@ -137,7 +137,8 @@ class Invitations
             return;
         }
 
-        $email = $this->entityManager->getEntity('Email');
+        $email = $this->entityManager->getNewEntity('Email');
+
         $email->set('to', $emailAddress);
 
         $subjectTpl = $this->templateFileManager->getTemplate('invitation', 'subject', $entity->getEntityType(), 'Crm');
diff --git a/application/Espo/Modules/Crm/Business/Reminder/EmailReminder.php b/application/Espo/Modules/Crm/Business/Reminder/EmailReminder.php
index 7a45dc593f..fae1e72ea9 100644
--- a/application/Espo/Modules/Crm/Business/Reminder/EmailReminder.php
+++ b/application/Espo/Modules/Crm/Business/Reminder/EmailReminder.php
@@ -119,7 +119,7 @@ class EmailReminder
             }
         }
 
-        $email = $this->entityManager->getEntity('Email');
+        $email = $this->entityManager->getNewEntity('Email');
 
         $email->set('to', $emailAddress);