diff --git a/packages/twenty-front/src/modules/object-record/hooks/__tests__/useCreateManyRecords.test.tsx b/packages/twenty-front/src/modules/object-record/hooks/__tests__/useCreateManyRecords.test.tsx
index 82ff949fe..1523b99c1 100644
--- a/packages/twenty-front/src/modules/object-record/hooks/__tests__/useCreateManyRecords.test.tsx
+++ b/packages/twenty-front/src/modules/object-record/hooks/__tests__/useCreateManyRecords.test.tsx
@@ -40,6 +40,20 @@ const mocks = [
       },
     })),
   },
+  {
+    request: {
+      query,
+      variables: {
+        data: input,
+        upsert: true,
+      },
+    },
+    result: jest.fn(() => ({
+      data: {
+        createPeople: response,
+      },
+    })),
+  },
 ];
 
 const Wrapper = getJestMetadataAndApolloMocksWrapper({
@@ -69,4 +83,28 @@ describe('useCreateManyRecords', () => {
     expect(mocks[0].result).toHaveBeenCalled();
     expect(mockRefetchAggregateQueries).toHaveBeenCalledTimes(1);
   });
+
+  it('does not indicate id in request variables when upsert is true because we cant know if it will be an insert or an update', async () => {
+    const { result } = renderHook(
+      () =>
+        useCreateManyRecords({
+          objectNameSingular: CoreObjectNameSingular.Person,
+        }),
+      {
+        wrapper: Wrapper,
+      },
+    );
+
+    await act(async () => {
+      const res = await result.current.createManyRecords(input, true);
+      expect(res).toEqual(response);
+    });
+
+    // Verify that the mutation was called with data without IDs
+    expect(mocks[1].request.variables.data).toEqual(input);
+    mocks[1].request.variables.data.forEach((record: any) => {
+      expect(record).not.toHaveProperty('id');
+    });
+    expect(mockRefetchAggregateQueries).toHaveBeenCalledTimes(1);
+  });
 });
diff --git a/packages/twenty-front/src/modules/object-record/hooks/useCreateManyRecords.ts b/packages/twenty-front/src/modules/object-record/hooks/useCreateManyRecords.ts
index 7880d575c..6cd54ae67 100644
--- a/packages/twenty-front/src/modules/object-record/hooks/useCreateManyRecords.ts
+++ b/packages/twenty-front/src/modules/object-record/hooks/useCreateManyRecords.ts
@@ -27,6 +27,10 @@ type PartialObjectRecordWithId = Partial<ObjectRecord> & {
   id: string;
 };
 
+type PartialObjectRecordWithOptionalId = Partial<ObjectRecord> & {
+  id?: string;
+};
+
 type useCreateManyRecordsProps = {
   objectNameSingular: string;
   recordGqlFields?: RecordGqlOperationGqlRecordFields;
@@ -75,16 +79,20 @@ export const useCreateManyRecords = <
     recordsToCreate: Partial<CreatedObjectRecord>[],
     upsert?: boolean,
   ) => {
-    const sanitizedCreateManyRecordsInput: PartialObjectRecordWithId[] = [];
+    const sanitizedCreateManyRecordsInput: PartialObjectRecordWithOptionalId[] =
+      [];
     const recordOptimisticRecordsInput: PartialObjectRecordWithId[] = [];
     recordsToCreate.forEach((recordToCreate) => {
-      const idForCreation = recordToCreate?.id ?? v4();
+      const shouldDoOptimisticEffect = upsert !== true;
+      const idForCreation = shouldDoOptimisticEffect
+        ? (recordToCreate?.id ?? v4())
+        : undefined;
       const sanitizedRecord = {
         ...sanitizeRecordInput({
           objectMetadataItem,
           recordInput: recordToCreate,
         }),
-        id: idForCreation,
+        ...(isDefined(idForCreation) ? { id: idForCreation } : {}),
       };
       const baseOptimisticRecordInputCreatedBy:
         | { createdBy: FieldActorForInputValue }
@@ -96,22 +104,25 @@ export const useCreateManyRecords = <
             },
           }
         : undefined;
-      const optimisticRecordInput = {
-        ...computeOptimisticRecordFromInput({
-          cache: apolloClient.cache,
-          objectMetadataItem,
-          objectMetadataItems,
-          currentWorkspaceMember: currentWorkspaceMember,
-          recordInput: {
-            ...baseOptimisticRecordInputCreatedBy,
-            ...recordToCreate,
-          },
-        }),
-        id: idForCreation,
-      };
 
       sanitizedCreateManyRecordsInput.push(sanitizedRecord);
-      recordOptimisticRecordsInput.push(optimisticRecordInput);
+
+      if (shouldDoOptimisticEffect) {
+        const optimisticRecordInput = {
+          ...computeOptimisticRecordFromInput({
+            cache: apolloClient.cache,
+            objectMetadataItem,
+            objectMetadataItems,
+            currentWorkspaceMember: currentWorkspaceMember,
+            recordInput: {
+              ...baseOptimisticRecordInputCreatedBy,
+              ...recordToCreate,
+            },
+          }),
+          id: idForCreation as string,
+        };
+        recordOptimisticRecordsInput.push(optimisticRecordInput);
+      }
     });
 
     const recordsCreatedInCache = recordOptimisticRecordsInput
diff --git a/packages/twenty-server/src/engine/api/graphql/graphql-query-runner/resolvers/graphql-query-create-many-resolver.service.ts b/packages/twenty-server/src/engine/api/graphql/graphql-query-runner/resolvers/graphql-query-create-many-resolver.service.ts
index 5418b9295..8391c57ba 100644
--- a/packages/twenty-server/src/engine/api/graphql/graphql-query-runner/resolvers/graphql-query-create-many-resolver.service.ts
+++ b/packages/twenty-server/src/engine/api/graphql/graphql-query-runner/resolvers/graphql-query-create-many-resolver.service.ts
@@ -266,15 +266,20 @@ export class GraphqlQueryCreateManyResolverService extends GraphqlQueryBaseResol
     for (const record of recordsToUpdate) {
       const recordId = record.id as string;
 
-      // TODO: we should align update and insert
-      // For insert, formating is done in the server
-      // While for update, formatting is done at the resolver level
-
-      const formattedRecord = formatData(
+      // we should not update an existing record's createdBy value
+      const recordWithoutCreatedByUpdate = this.getRecordWithoutCreatedBy(
         record,
         objectMetadataItemWithFieldMaps,
       );
 
+      const formattedRecord = formatData(
+        recordWithoutCreatedByUpdate,
+        objectMetadataItemWithFieldMaps,
+      );
+
+      // TODO: we should align update and insert
+      // For insert, formating is done in the server
+      // While for update, formatting is done at the resolver level
       await repository.update(recordId, formattedRecord);
       result.identifiers.push({ id: recordId });
       result.generatedMaps.push({ id: recordId });
@@ -362,6 +367,25 @@ export class GraphqlQueryCreateManyResolverService extends GraphqlQueryBaseResol
     );
   }
 
+  private getRecordWithoutCreatedBy(
+    record: Partial<ObjectRecord>,
+    objectMetadataItemWithFieldMaps: ObjectMetadataItemWithFieldMaps,
+  ) {
+    let recordWithoutCreatedByUpdate = record;
+
+    if (
+      'createdBy' in record &&
+      objectMetadataItemWithFieldMaps.fieldsByName['createdBy']?.isCustom ===
+        false
+    ) {
+      const { createdBy: _createdBy, ...recordWithoutCreatedBy } = record;
+
+      recordWithoutCreatedByUpdate = recordWithoutCreatedBy;
+    }
+
+    return recordWithoutCreatedByUpdate;
+  }
+
   async validate<T extends ObjectRecord>(
     args: CreateManyResolverArgs<Partial<T>>,
     options: WorkspaceQueryRunnerOptions,
diff --git a/packages/twenty-server/src/engine/twenty-orm/utils/format-data.util.ts b/packages/twenty-server/src/engine/twenty-orm/utils/format-data.util.ts
index ac9bb9805..05db3e9cf 100644
--- a/packages/twenty-server/src/engine/twenty-orm/utils/format-data.util.ts
+++ b/packages/twenty-server/src/engine/twenty-orm/utils/format-data.util.ts
@@ -1,5 +1,5 @@
-import { capitalize } from 'twenty-shared/utils';
 import { FieldMetadataType } from 'twenty-shared/types';
+import { capitalize } from 'twenty-shared/utils';
 
 import { FieldMetadataInterface } from 'src/engine/metadata-modules/field-metadata/interfaces/field-metadata.interface';