diff --git a/application/Espo/Controllers/MassAction.php b/application/Espo/Controllers/MassAction.php
index a8c0caf844..65a7234680 100644
--- a/application/Espo/Controllers/MassAction.php
+++ b/application/Espo/Controllers/MassAction.php
@@ -30,6 +30,7 @@
 namespace Espo\Controllers;
 
 use Espo\Core\Exceptions\BadRequest;
+use Espo\Core\Exceptions\Error;
 
 use Espo\Core\MassAction\Service;
 use Espo\Core\MassAction\ServiceResult;
@@ -139,6 +140,10 @@ class MassAction
 
         $result = $serviceResult->getResult();
 
+        if (!$result) {
+            throw new Error();
+        }
+
         $data = (object) [];
 
         if ($result->hasCount()) {
diff --git a/application/Espo/Core/Acl/DefaultOwnershipChecker.php b/application/Espo/Core/Acl/DefaultOwnershipChecker.php
index 51006315c4..21dda5ac89 100644
--- a/application/Espo/Core/Acl/DefaultOwnershipChecker.php
+++ b/application/Espo/Core/Acl/DefaultOwnershipChecker.php
@@ -78,7 +78,9 @@ class DefaultOwnershipChecker implements OwnershipOwnChecker, OwnershipTeamCheck
 
     public function checkTeam(User $user, Entity $entity): bool
     {
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            return false;
+        }
 
         $userTeamIdList = $user->getLinkMultipleIdList(self::FIELD_TEAMS);
 
diff --git a/application/Espo/Core/Authentication/AuthToken/EspoManager.php b/application/Espo/Core/Authentication/AuthToken/EspoManager.php
index 0199daf674..0499bd2f9f 100644
--- a/application/Espo/Core/Authentication/AuthToken/EspoManager.php
+++ b/application/Espo/Core/Authentication/AuthToken/EspoManager.php
@@ -103,7 +103,9 @@ class EspoManager implements Manager
 
     public function inactivate(AuthToken $authToken): void
     {
-        assert($authToken instanceof AuthTokenEntity);
+        if (!$authToken instanceof AuthTokenEntity) {
+            throw new RuntimeException();
+        }
 
         $this->validateNotChanged($authToken);
 
@@ -114,7 +116,9 @@ class EspoManager implements Manager
 
     public function renew(AuthToken $authToken): void
     {
-        assert($authToken instanceof AuthTokenEntity);
+        if (!$authToken instanceof AuthTokenEntity) {
+            throw new RuntimeException();
+        }
 
         $this->validateNotChanged($authToken);
 
diff --git a/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedManyType.php b/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedManyType.php
index 5b8b8a59fd..017bc15b44 100644
--- a/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedManyType.php
+++ b/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedManyType.php
@@ -115,7 +115,11 @@ class FindRelatedManyType extends BaseFunction implements
             $order = $order ?? 'asc';
         }
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            $this->throwError("Only core entities are supported.");
+
+            return;
+        }
 
         $relationType = $entity->getRelationParam($link, 'type');
 
diff --git a/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedOneType.php b/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedOneType.php
index b484140753..71029b6d51 100644
--- a/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedOneType.php
+++ b/application/Espo/Core/Formula/Functions/RecordGroup/FindRelatedOneType.php
@@ -90,7 +90,11 @@ class FindRelatedOneType extends BaseFunction implements
 
         $metadata = $this->metadata;
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            $this->throwError("Only core entities are supported.");
+
+            return;
+        }
 
         $relationType = $entity->getRelationParam($link, 'type');
 
diff --git a/application/Espo/Core/Mail/Importer.php b/application/Espo/Core/Mail/Importer.php
index c9b295d9d7..f443eef6f3 100644
--- a/application/Espo/Core/Mail/Importer.php
+++ b/application/Espo/Core/Mail/Importer.php
@@ -444,7 +444,9 @@ class Importer
             return;
         }
 
-        assert($parent instanceof CoreEntity);
+        if (!$parent instanceof CoreEntity) {
+            return;
+        }
 
         $parentTeamIdList = $parent->getLinkMultipleIdList('teams');
 
diff --git a/application/Espo/Core/MassAction/Jobs/Process.php b/application/Espo/Core/MassAction/Jobs/Process.php
index da469aeac8..5190e3fd7b 100644
--- a/application/Espo/Core/MassAction/Jobs/Process.php
+++ b/application/Espo/Core/MassAction/Jobs/Process.php
@@ -66,8 +66,6 @@ class Process implements Job
     {
         $id = $data->getTargetId();
 
-        assert($id !== null);
-
         if ($id === null) {
             throw new Error("ID not passed to the mass action job.");
         }
diff --git a/application/Espo/Core/MassAction/ServiceResult.php b/application/Espo/Core/MassAction/ServiceResult.php
index 874e58912c..6c9ea99173 100644
--- a/application/Espo/Core/MassAction/ServiceResult.php
+++ b/application/Espo/Core/MassAction/ServiceResult.php
@@ -48,17 +48,13 @@ class ServiceResult
         return $this->result !== null;
     }
 
-    public function getId(): string
+    public function getId(): ?string
     {
-        assert($this->id !== null);
-
         return $this->id;
     }
 
-    public function getResult(): Result
+    public function getResult(): ?Result
     {
-        assert($this->result !== null);
-
         return $this->result;
     }
 
diff --git a/application/Espo/Core/Notification/DefaultAssignmentNotificator.php b/application/Espo/Core/Notification/DefaultAssignmentNotificator.php
index 6e8cb324e5..c03adbcc67 100644
--- a/application/Espo/Core/Notification/DefaultAssignmentNotificator.php
+++ b/application/Espo/Core/Notification/DefaultAssignmentNotificator.php
@@ -65,7 +65,9 @@ class DefaultAssignmentNotificator implements AssignmentNotificator
 
     public function process(Entity $entity, Params $params): void
     {
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            return;
+        }
 
         if ($entity->hasLinkMultipleField('assignedUsers')) {
             $userIdList = $entity->getLinkMultipleIdList('assignedUsers');
diff --git a/application/Espo/Core/Portal/Loaders/Acl.php b/application/Espo/Core/Portal/Loaders/Acl.php
index 4c7456495d..a76f152a7f 100644
--- a/application/Espo/Core/Portal/Loaders/Acl.php
+++ b/application/Espo/Core/Portal/Loaders/Acl.php
@@ -31,6 +31,8 @@ namespace Espo\Core\Portal\Loaders;
 
 use Espo\Core\Portal\AclManager as PortalAclManager;
 
+use InvalidArgumentException;
+
 use Espo\Core\{
     Container\Loader,
     AclManager,
@@ -48,7 +50,9 @@ class Acl implements Loader
 
     public function __construct(AclManager $aclManager, User $user)
     {
-        assert($aclManager instanceof PortalAclManager);
+        if (!$aclManager instanceof PortalAclManager) {
+            throw new InvalidArgumentException();
+        }
 
         $this->aclManager = $aclManager;
         $this->user = $user;
diff --git a/application/Espo/Core/Record/Service.php b/application/Espo/Core/Record/Service.php
index 71850ea75c..0c0d22e6c5 100644
--- a/application/Espo/Core/Record/Service.php
+++ b/application/Espo/Core/Record/Service.php
@@ -1026,7 +1026,9 @@ class Service implements Crud,
             throw new NotFound();
         }
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            throw new Error("Only core entities are supported");
+        }
 
         if ($this->noEditAccessRequiredForLink) {
             if (!$this->acl->check($entity, AclTable::ACTION_READ)) {
@@ -1098,7 +1100,9 @@ class Service implements Crud,
             throw new NotFound();
         }
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            throw new Error("Only core entities are supported");
+        }
 
         if ($this->noEditAccessRequiredForLink) {
             if (!$this->acl->check($entity, AclTable::ACTION_READ)) {
@@ -1160,14 +1164,13 @@ class Service implements Crud,
             throw new NotFound();
         }
 
+        /** @var User|null $user */
         $user = $this->entityManager->getEntity('User', $foreignId);
 
         if (!$user) {
             throw new NotFound();
         }
 
-        assert($user instanceof User);
-
         if (!$this->acl->check($entity, AclTable::ACTION_EDIT)) {
             throw new ForbiddenSilent("No 'edit' access.");
         }
@@ -1215,14 +1218,13 @@ class Service implements Crud,
             throw new NotFound();
         }
 
+        /** @var User|null $user */
         $user = $this->entityManager->getEntity('User', $foreignId);
 
         if (!$user) {
             throw new NotFound();
         }
 
-        assert($user instanceof User);
-
         if (!$this->acl->check($entity, AclTable::ACTION_EDIT)) {
             throw new ForbiddenSilent("No 'edit' access.");
         }
@@ -1278,7 +1280,9 @@ class Service implements Crud,
             return $this->$methodName($id, $searchParams);
         }
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            throw new Error("Only core entities are supported");
+        }
 
         $foreignEntityType = $entity->getRelationParam($link, 'entity');
 
@@ -1623,7 +1627,9 @@ class Service implements Crud,
                 }
             }
             else if ($type === 'linkMultiple') {
-                assert($entity instanceof CoreEntity);
+                if (!$entity instanceof CoreEntity) {
+                    throw new Error("Only core entities are supported");
+                }
 
                 $foreignLink = $entity->getRelationParam($field, 'foreign');
                 $foreignEntityType = $entity->getRelationParam($field, 'entity');
diff --git a/application/Espo/Entities/MassAction.php b/application/Espo/Entities/MassAction.php
index 1dbe724c2d..7d59a495c8 100644
--- a/application/Espo/Entities/MassAction.php
+++ b/application/Espo/Entities/MassAction.php
@@ -36,6 +36,8 @@ use Espo\Core\Field\Link;
 use Espo\Core\MassAction\Data;
 use Espo\Core\MassAction\Params;
 
+use Espo\Core\Exceptions\Error;
+
 use stdClass;
 
 class MassAction extends Entity
@@ -54,12 +56,13 @@ class MassAction extends Entity
     {
         $raw = $this->get('params');
 
-        assert(is_string($raw));
+        if (!is_string($raw)) {
+            throw new Error("No 'params'.");
+        }
 
+        /** @var Params $params */
         $params = unserialize($raw);
 
-        assert($params instanceof Params);
-
         return $params;
     }
 
@@ -67,7 +70,9 @@ class MassAction extends Entity
     {
         $raw = $this->get('data');
 
-        assert($raw instanceof stdClass);
+        if (!$raw instanceof stdClass) {
+            throw new Error("No 'data'.");
+        }
 
         return Data::fromRaw($raw);
     }
@@ -76,7 +81,9 @@ class MassAction extends Entity
     {
         $value = $this->get('entityType');
 
-        assert(is_string($value));
+        if (!is_string($value)) {
+            throw new Error("No 'entityType'.");
+        }
 
         return $value;
     }
@@ -85,7 +92,9 @@ class MassAction extends Entity
     {
         $value = $this->get('action');
 
-        assert(is_string($value));
+        if (!is_string($value)) {
+            throw new Error("No 'action'.");
+        }
 
         return $value;
     }
@@ -94,7 +103,9 @@ class MassAction extends Entity
     {
         $value = $this->get('status');
 
-        assert(is_string($value));
+        if (!is_string($value)) {
+            throw new Error("No 'status'.");
+        }
 
         return $value;
     }
@@ -108,7 +119,9 @@ class MassAction extends Entity
     {
         $value = $this->getValueObject('createdAt');
 
-        assert($value instanceof DateTime);
+        if (!$value instanceof DateTime) {
+            throw new Error("No 'createdAt'.");
+        }
 
         return $value;
     }
@@ -117,7 +130,9 @@ class MassAction extends Entity
     {
         $value = $this->getValueObject('createdBy');
 
-        assert($value instanceof Link);
+        if (!$value instanceof Link) {
+            throw new Error("No 'createdBy'.");
+        }
 
         return $value;
     }
diff --git a/application/Espo/ORM/Repository/RDBRepository.php b/application/Espo/ORM/Repository/RDBRepository.php
index fa3ab590ff..117fc5c618 100644
--- a/application/Espo/ORM/Repository/RDBRepository.php
+++ b/application/Espo/ORM/Repository/RDBRepository.php
@@ -209,7 +209,9 @@ class RDBRepository implements Repository
     {
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'restoreDeleted'.");
+        }
 
         $mapper->restoreDeleted($this->entityType, $id);
     }
@@ -245,7 +247,9 @@ class RDBRepository implements Repository
     {
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'deleteFromDb'.");
+        }
 
         $mapper->deleteFromDb($this->entityType, $id, $onlyDeleted);
     }
@@ -287,7 +291,9 @@ class RDBRepository implements Repository
     {
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'findBySql'.");
+        }
 
         return $mapper->selectBySql($this->entityType, $sql);
     }
diff --git a/application/Espo/ORM/Repository/RDBSelectBuilder.php b/application/Espo/ORM/Repository/RDBSelectBuilder.php
index 20e0ced968..94597c5257 100644
--- a/application/Espo/ORM/Repository/RDBSelectBuilder.php
+++ b/application/Espo/ORM/Repository/RDBSelectBuilder.php
@@ -153,7 +153,9 @@ class RDBSelectBuilder
 
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'max'.");
+        }
 
         return $mapper->max($query, $attribute);
     }
@@ -169,7 +171,9 @@ class RDBSelectBuilder
 
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'min'.");
+        }
 
         return $mapper->min($query, $attribute);
     }
@@ -185,7 +189,9 @@ class RDBSelectBuilder
 
         $mapper = $this->getMapper();
 
-        assert($mapper instanceof BaseMapper);
+        if (!$mapper instanceof BaseMapper) {
+            throw new RuntimeException("Not supported 'sum'.");
+        }
 
         return $mapper->sum($query, $attribute);
     }
diff --git a/application/Espo/Tools/EmailNotification/AssignmentProcessor.php b/application/Espo/Tools/EmailNotification/AssignmentProcessor.php
index d4c9d5ae4d..3f02209994 100644
--- a/application/Espo/Tools/EmailNotification/AssignmentProcessor.php
+++ b/application/Espo/Tools/EmailNotification/AssignmentProcessor.php
@@ -145,7 +145,9 @@ class AssignmentProcessor
             return;
         }
 
-        assert($entity instanceof Entity);
+        if (!$entity instanceof Entity) {
+            return;
+        }
 
         $this->loadParentNameFields($entity);
 
diff --git a/application/Espo/Tools/Import/Import.php b/application/Espo/Tools/Import/Import.php
index 0c816fb550..93dbe4a4e9 100644
--- a/application/Espo/Tools/Import/Import.php
+++ b/application/Espo/Tools/Import/Import.php
@@ -448,7 +448,9 @@ class Import
             $entity = $this->entityManager->getEntity($this->entityType);
         }
 
-        assert($entity instanceof Entity);
+        if (!$entity instanceof Entity) {
+            throw new Error("Import supports only `Espo\Core\ORM\Entity`.");
+        }
 
         $isNew = $entity->isNew();
 
diff --git a/application/Espo/Tools/Notification/HookProcessor.php b/application/Espo/Tools/Notification/HookProcessor.php
index 779964e503..8f41b2820e 100644
--- a/application/Espo/Tools/Notification/HookProcessor.php
+++ b/application/Espo/Tools/Notification/HookProcessor.php
@@ -89,7 +89,9 @@ class HookProcessor
     {
         $entityType = $entity->getEntityType();
 
-        assert($entity instanceof CoreEntity);
+        if (!$entity instanceof CoreEntity) {
+            return;
+        }
 
         /**
          * No need to process assignment notifications for entity types that have Stream enabled.