diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5a856ca09..115d25a92 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fixed the handling of the _Exclude from Analysis_ tag in the activities table
+- Fixed the persistence of an empty comment in the create or update account dialog
 - Resolved a validation error caused by empty strings in the asset profile details dialog of the admin control panel
 
 ## 3.39.0 - 2026-08-01
diff --git a/apps/client/src/app/pages/accounts/create-or-update-account-dialog/create-or-update-account-dialog.component.ts b/apps/client/src/app/pages/accounts/create-or-update-account-dialog/create-or-update-account-dialog.component.ts
index 8b0536ebf..2157ea5d3 100644
--- a/apps/client/src/app/pages/accounts/create-or-update-account-dialog/create-or-update-account-dialog.component.ts
+++ b/apps/client/src/app/pages/accounts/create-or-update-account-dialog/create-or-update-account-dialog.component.ts
@@ -1,6 +1,7 @@
 import { UserService } from '@ghostfolio/client/services/user/user.service';
 import { TAG_ID_EXCLUDE_FROM_ANALYSIS } from '@ghostfolio/common/config';
 import { CreateAccountDto, UpdateAccountDto } from '@ghostfolio/common/dtos';
+import { getStringOrNull } from '@ghostfolio/common/helper';
 import { hasPermission, permissions } from '@ghostfolio/common/permissions';
 import { validateObjectForForm } from '@ghostfolio/common/utils';
 import { GfCurrencySelectorComponent } from '@ghostfolio/ui/currency-selector';
@@ -198,7 +199,7 @@ export class GfCreateOrUpdateAccountDialogComponent {
   protected async onSubmit() {
     const account: CreateAccountDto | UpdateAccountDto = {
       balance: this.accountForm.get('balance')?.value,
-      comment: this.accountForm.get('comment')?.value ?? null,
+      comment: getStringOrNull(this.accountForm.get('comment')?.value),
       currency: this.accountForm.get('currency')?.value,
       id: this.accountForm.get('accountId')?.value,
       name: this.accountForm.get('name')?.value,
diff --git a/apps/client/src/app/pages/portfolio/activities/create-or-update-activity-dialog/create-or-update-activity-dialog.component.ts b/apps/client/src/app/pages/portfolio/activities/create-or-update-activity-dialog/create-or-update-activity-dialog.component.ts
index 632db1cd4..3b80d2825 100644
--- a/apps/client/src/app/pages/portfolio/activities/create-or-update-activity-dialog/create-or-update-activity-dialog.component.ts
+++ b/apps/client/src/app/pages/portfolio/activities/create-or-update-activity-dialog/create-or-update-activity-dialog.component.ts
@@ -1,7 +1,10 @@
 import { UserService } from '@ghostfolio/client/services/user/user.service';
 import { ASSET_CLASS_MAPPING, DEFAULT_LOCALE } from '@ghostfolio/common/config';
 import { CreateOrderDto, UpdateOrderDto } from '@ghostfolio/common/dtos';
-import { getDateFormatString } from '@ghostfolio/common/helper';
+import {
+  getDateFormatString,
+  getStringOrNull
+} from '@ghostfolio/common/helper';
 import {
   AssetClassSelectorOption,
   LookupItem
@@ -471,7 +474,7 @@ export class GfCreateOrUpdateActivityDialogComponent {
       accountId: this.activityForm.get('accountId')?.value,
       assetClass: this.activityForm.get('assetClass')?.value,
       assetSubClass: this.activityForm.get('assetSubClass')?.value,
-      comment: this.activityForm.get('comment')?.value ?? null,
+      comment: getStringOrNull(this.activityForm.get('comment')?.value),
       currency: this.activityForm.get('currency')?.value,
       customCurrency: this.activityForm.get('currencyOfUnitPrice')?.value,
       dataSource: ['FEE', 'INTEREST', 'LIABILITY', 'VALUABLE'].includes(
diff --git a/libs/common/src/lib/dtos/create-account.dto.ts b/libs/common/src/lib/dtos/create-account.dto.ts
index e4a0c64fe..cae8293ee 100644
--- a/libs/common/src/lib/dtos/create-account.dto.ts
+++ b/libs/common/src/lib/dtos/create-account.dto.ts
@@ -20,7 +20,7 @@ export class CreateAccountDto {
   @Transform(({ value }: TransformFnParams) =>
     isString(value) ? value.trim() : value
   )
-  comment?: string;
+  comment?: string | null;
 
   @IsCurrencyCode()
   currency: string;
diff --git a/libs/common/src/lib/dtos/create-order.dto.ts b/libs/common/src/lib/dtos/create-order.dto.ts
index 36365b7be..c70b66b02 100644
--- a/libs/common/src/lib/dtos/create-order.dto.ts
+++ b/libs/common/src/lib/dtos/create-order.dto.ts
@@ -35,7 +35,7 @@ export class CreateOrderDto {
   @Transform(({ value }: TransformFnParams) =>
     isString(value) ? value.trim() : value
   )
-  comment?: string;
+  comment?: string | null;
 
   @IsCurrencyCode()
   currency: string;
diff --git a/libs/common/src/lib/dtos/update-account.dto.ts b/libs/common/src/lib/dtos/update-account.dto.ts
index a6a3e6ac6..d8bfc7b8d 100644
--- a/libs/common/src/lib/dtos/update-account.dto.ts
+++ b/libs/common/src/lib/dtos/update-account.dto.ts
@@ -20,7 +20,7 @@ export class UpdateAccountDto {
   @Transform(({ value }: TransformFnParams) =>
     isString(value) ? value.trim() : value
   )
-  comment?: string;
+  comment?: string | null;
 
   @IsCurrencyCode()
   currency: string;
diff --git a/libs/common/src/lib/dtos/update-order.dto.ts b/libs/common/src/lib/dtos/update-order.dto.ts
index 991479bc8..d8fdbe66b 100644
--- a/libs/common/src/lib/dtos/update-order.dto.ts
+++ b/libs/common/src/lib/dtos/update-order.dto.ts
@@ -34,7 +34,7 @@ export class UpdateOrderDto {
   @Transform(({ value }: TransformFnParams) =>
     isString(value) ? value.trim() : value
   )
-  comment?: string;
+  comment?: string | null;
 
   @IsCurrencyCode()
   currency: string;