diff --git a/packages/twenty-server/src/engine/workspace-manager/workspace-migration-runner/utils/convert-on-delete-action-to-on-delete.util.ts b/packages/twenty-server/src/engine/workspace-manager/workspace-migration-runner/utils/convert-on-delete-action-to-on-delete.util.ts
index 5bdb4e08f..73e36ba67 100644
--- a/packages/twenty-server/src/engine/workspace-manager/workspace-migration-runner/utils/convert-on-delete-action-to-on-delete.util.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/workspace-migration-runner/utils/convert-on-delete-action-to-on-delete.util.ts
@@ -3,10 +3,6 @@ import { RelationOnDeleteAction } from 'src/engine/metadata-modules/relation-met
 export const convertOnDeleteActionToOnDelete = (
   onDeleteAction: RelationOnDeleteAction | undefined,
 ): 'CASCADE' | 'SET NULL' | 'RESTRICT' | 'NO ACTION' | undefined => {
-  if (!onDeleteAction) {
-    return 'SET NULL';
-  }
-
   switch (onDeleteAction) {
     case 'CASCADE':
       return 'CASCADE';
diff --git a/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/decorators/relation-metadata.decorator.ts b/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/decorators/relation-metadata.decorator.ts
index 3307f6093..2981b4f9c 100644
--- a/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/decorators/relation-metadata.decorator.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/decorators/relation-metadata.decorator.ts
@@ -6,7 +6,6 @@ import {
 } from 'src/engine/workspace-manager/workspace-sync-metadata/interfaces/reflect-relation-metadata.interface';
 
 import { TypedReflect } from 'src/utils/typed-reflect';
-import { RelationOnDeleteAction } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
 
 export function RelationMetadata<TClass extends object>(
   params: RelationMetadataDecoratorParams<TClass>,
@@ -27,7 +26,6 @@ export function RelationMetadata<TClass extends object>(
           target,
           fieldKey,
           ...params,
-          onDelete: params.onDelete ?? RelationOnDeleteAction.SET_NULL,
           gate,
         } satisfies ReflectRelationMetadata,
       ],
diff --git a/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/interfaces/reflect-relation-metadata.interface.ts b/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/interfaces/reflect-relation-metadata.interface.ts
index 32282798f..13f8c1a0d 100644
--- a/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/interfaces/reflect-relation-metadata.interface.ts
+++ b/packages/twenty-server/src/engine/workspace-manager/workspace-sync-metadata/interfaces/reflect-relation-metadata.interface.ts
@@ -11,7 +11,7 @@ export interface RelationMetadataDecoratorParams<T> {
   type: RelationMetadataType;
   inverseSideTarget: () => ObjectType<T>;
   inverseSideFieldKey?: keyof T;
-  onDelete?: RelationOnDeleteAction;
+  onDelete: RelationOnDeleteAction;
 }
 
 export interface ReflectRelationMetadata
diff --git a/packages/twenty-server/src/modules/activity/standard-objects/activity.object-metadata.ts b/packages/twenty-server/src/modules/activity/standard-objects/activity.object-metadata.ts
index 452ff189a..8a49be75f 100644
--- a/packages/twenty-server/src/modules/activity/standard-objects/activity.object-metadata.ts
+++ b/packages/twenty-server/src/modules/activity/standard-objects/activity.object-metadata.ts
@@ -1,5 +1,8 @@
 import { FieldMetadataType } from 'src/engine/metadata-modules/field-metadata/field-metadata.entity';
-import { RelationMetadataType } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
+import {
+  RelationMetadataType,
+  RelationOnDeleteAction,
+} from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
 import { activityStandardFieldIds } from 'src/engine/workspace-manager/workspace-sync-metadata/constants/standard-field-ids';
 import { standardObjectIds } from 'src/engine/workspace-manager/workspace-sync-metadata/constants/standard-object-ids';
 import { FieldMetadata } from 'src/engine/workspace-manager/workspace-sync-metadata/decorators/field-metadata.decorator';
@@ -91,6 +94,7 @@ export class ActivityObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ActivityTargetObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   activityTargets: ActivityTargetObjectMetadata[];
@@ -105,6 +109,7 @@ export class ActivityObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => AttachmentObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   attachments: AttachmentObjectMetadata[];
@@ -119,6 +124,7 @@ export class ActivityObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => CommentObjectMetadata,
+    onDelete: RelationOnDeleteAction.CASCADE,
   })
   @IsNullable()
   comments: CommentObjectMetadata[];
@@ -131,6 +137,7 @@ export class ActivityObjectMetadata extends BaseObjectMetadata {
     icon: 'IconUserCircle',
     joinColumn: 'authorId',
   })
+  @IsNullable()
   author: WorkspaceMemberObjectMetadata;
 
   @FieldMetadata({
diff --git a/packages/twenty-server/src/modules/company/standard-objects/company.object-metadata.ts b/packages/twenty-server/src/modules/company/standard-objects/company.object-metadata.ts
index af5db2ed7..78ebe912e 100644
--- a/packages/twenty-server/src/modules/company/standard-objects/company.object-metadata.ts
+++ b/packages/twenty-server/src/modules/company/standard-objects/company.object-metadata.ts
@@ -132,6 +132,7 @@ export class CompanyObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => PersonObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   people: PersonObjectMetadata[];
@@ -173,6 +174,7 @@ export class CompanyObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => OpportunityObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   opportunities: OpportunityObjectMetadata[];
diff --git a/packages/twenty-server/src/modules/opportunity/standard-objects/opportunity.object-metadata.ts b/packages/twenty-server/src/modules/opportunity/standard-objects/opportunity.object-metadata.ts
index 2708cc2fa..c8353dd13 100644
--- a/packages/twenty-server/src/modules/opportunity/standard-objects/opportunity.object-metadata.ts
+++ b/packages/twenty-server/src/modules/opportunity/standard-objects/opportunity.object-metadata.ts
@@ -163,6 +163,7 @@ export class OpportunityObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => AttachmentObjectMetadata,
+    onDelete: RelationOnDeleteAction.CASCADE,
   })
   @IsNullable()
   attachments: AttachmentObjectMetadata[];
@@ -177,6 +178,7 @@ export class OpportunityObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => EventObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   events: EventObjectMetadata[];
diff --git a/packages/twenty-server/src/modules/person/standard-objects/person.object-metadata.ts b/packages/twenty-server/src/modules/person/standard-objects/person.object-metadata.ts
index 85a4afe97..afed4319a 100644
--- a/packages/twenty-server/src/modules/person/standard-objects/person.object-metadata.ts
+++ b/packages/twenty-server/src/modules/person/standard-objects/person.object-metadata.ts
@@ -142,6 +142,7 @@ export class PersonObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => OpportunityObjectMetadata,
     inverseSideFieldKey: 'pointOfContact',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   pointOfContactForOpportunities: OpportunityObjectMetadata[];
 
@@ -199,6 +200,7 @@ export class PersonObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => MessageParticipantObjectMetadata,
     inverseSideFieldKey: 'person',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsSystem()
   messageParticipants: MessageParticipantObjectMetadata[];
@@ -213,6 +215,7 @@ export class PersonObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => CalendarEventAttendeeObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @Gate({
     featureFlag: 'IS_CALENDAR_ENABLED',
diff --git a/packages/twenty-server/src/modules/view/standard-objects/view.object-metadata.ts b/packages/twenty-server/src/modules/view/standard-objects/view.object-metadata.ts
index c644497b8..91705f1ea 100644
--- a/packages/twenty-server/src/modules/view/standard-objects/view.object-metadata.ts
+++ b/packages/twenty-server/src/modules/view/standard-objects/view.object-metadata.ts
@@ -1,5 +1,8 @@
 import { FieldMetadataType } from 'src/engine/metadata-modules/field-metadata/field-metadata.entity';
-import { RelationMetadataType } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
+import {
+  RelationMetadataType,
+  RelationOnDeleteAction,
+} from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
 import { viewStandardFieldIds } from 'src/engine/workspace-manager/workspace-sync-metadata/constants/standard-field-ids';
 import { standardObjectIds } from 'src/engine/workspace-manager/workspace-sync-metadata/constants/standard-object-ids';
 import { FieldMetadata } from 'src/engine/workspace-manager/workspace-sync-metadata/decorators/field-metadata.decorator';
@@ -102,6 +105,7 @@ export class ViewObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ViewFieldObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   viewFields: ViewFieldObjectMetadata[];
@@ -116,6 +120,7 @@ export class ViewObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ViewFilterObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   viewFilters: ViewFilterObjectMetadata[];
@@ -130,6 +135,7 @@ export class ViewObjectMetadata extends BaseObjectMetadata {
   @RelationMetadata({
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ViewSortObjectMetadata,
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @IsNullable()
   viewSorts: ViewSortObjectMetadata[];
diff --git a/packages/twenty-server/src/modules/workspace-member/standard-objects/workspace-member.object-metadata.ts b/packages/twenty-server/src/modules/workspace-member/standard-objects/workspace-member.object-metadata.ts
index 86cd02db1..036bc2f6c 100644
--- a/packages/twenty-server/src/modules/workspace-member/standard-objects/workspace-member.object-metadata.ts
+++ b/packages/twenty-server/src/modules/workspace-member/standard-objects/workspace-member.object-metadata.ts
@@ -102,6 +102,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ActivityObjectMetadata,
     inverseSideFieldKey: 'author',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   authoredActivities: ActivityObjectMetadata[];
 
@@ -116,6 +117,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => ActivityObjectMetadata,
     inverseSideFieldKey: 'assignee',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   assignedActivities: ActivityObjectMetadata[];
 
@@ -144,6 +146,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => CompanyObjectMetadata,
     inverseSideFieldKey: 'accountOwner',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   accountOwnerForCompanies: CompanyObjectMetadata[];
 
@@ -158,6 +161,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => AttachmentObjectMetadata,
     inverseSideFieldKey: 'author',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   authoredAttachments: AttachmentObjectMetadata[];
 
@@ -172,6 +176,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => CommentObjectMetadata,
     inverseSideFieldKey: 'author',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   authoredComments: CommentObjectMetadata[];
 
@@ -201,6 +206,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => MessageParticipantObjectMetadata,
     inverseSideFieldKey: 'workspaceMember',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   messageParticipants: MessageParticipantObjectMetadata[];
 
@@ -215,6 +221,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => BlocklistObjectMetadata,
     inverseSideFieldKey: 'workspaceMember',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   blocklist: BlocklistObjectMetadata[];
 
@@ -229,6 +236,7 @@ export class WorkspaceMemberObjectMetadata extends BaseObjectMetadata {
     type: RelationMetadataType.ONE_TO_MANY,
     inverseSideTarget: () => CalendarEventAttendeeObjectMetadata,
     inverseSideFieldKey: 'workspaceMember',
+    onDelete: RelationOnDeleteAction.SET_NULL,
   })
   @Gate({
     featureFlag: 'IS_CALENDAR_ENABLED',