diff --git a/src/function/child/set-primary-device.ts b/src/function/child/set-primary-device.ts
index 6da1e21..5c0ede8 100644
--- a/src/function/child/set-primary-device.ts
+++ b/src/function/child/set-primary-device.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -16,7 +16,6 @@
  */
 
 import { Conflict, InternalServerError, Unauthorized } from 'http-errors'
-import * as Sequelize from 'sequelize'
 import { config } from '../../config'
 import { Database } from '../../database'
 import { generateVersionId } from '../../util/token'
@@ -60,7 +59,6 @@ export const setPrimaryDevice = async ({ database, websocket, deviceAuthToken, c
         userId: deviceEntry.currentUserId
       },
       transaction,
-      lock: Sequelize.Transaction.LOCK.UPDATE,
       attributes: ['currentDevice']
     })
 
diff --git a/src/function/parent/link-mail-address.ts b/src/function/parent/link-mail-address.ts
index 7c3ecb6..39682b9 100644
--- a/src/function/parent/link-mail-address.ts
+++ b/src/function/parent/link-mail-address.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -16,7 +16,6 @@
  */
 
 import { Conflict, Unauthorized } from 'http-errors'
-import * as Sequelize from 'sequelize'
 import { Database } from '../../database'
 import { generateVersionId } from '../../util/token'
 import { WebsocketApi } from '../../websocket'
@@ -65,8 +64,7 @@ export const linkMailAddress = async ({ mailAuthToken, deviceAuthToken, parentUs
         familyId,
         userId: parentUserId
       },
-      transaction,
-      lock: Sequelize.Transaction.LOCK.UPDATE
+      transaction
     })
 
     if (!parentEntry) {
diff --git a/src/function/purchase/add-purchase.ts b/src/function/purchase/add-purchase.ts
index 5078155..959e3ca 100644
--- a/src/function/purchase/add-purchase.ts
+++ b/src/function/purchase/add-purchase.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -16,7 +16,6 @@
  */
 
 import { Conflict } from 'http-errors'
-import * as Sequelize from 'sequelize'
 import { Database, Transaction } from '../../database'
 import { notifyClientsAboutChangesDelayed } from '../../function/websocket'
 import { WebsocketApi } from '../../websocket'
@@ -51,8 +50,7 @@ export const addPurchase = async ({ database, familyId, type, transactionId, web
     where: {
       familyId
     },
-    transaction,
-    lock: Sequelize.Transaction.LOCK.UPDATE
+    transaction
   })
 
   if (!familyEntry) {
diff --git a/src/function/sync/apply-actions/dispatch-child-action/childchangepassword.ts b/src/function/sync/apply-actions/dispatch-child-action/childchangepassword.ts
index ceecdfe..0011bf5 100644
--- a/src/function/sync/apply-actions/dispatch-child-action/childchangepassword.ts
+++ b/src/function/sync/apply-actions/dispatch-child-action/childchangepassword.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -15,7 +15,6 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import * as Sequelize from 'sequelize'
 import { ChildChangePasswordAction } from '../../../../action'
 import { Cache } from '../cache'
 import { SourceUserNotFoundException } from '../exception/illegal-state'
@@ -31,8 +30,7 @@ export const dispatchChildChangePassword = async ({ action, childUserId, cache }
       userId: childUserId,
       type: 'child'
     },
-    transaction: cache.transaction,
-    lock: Sequelize.Transaction.LOCK.UPDATE
+    transaction: cache.transaction
   })
 
   if (!childEntry) {
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/changeparentpassword.ts b/src/function/sync/apply-actions/dispatch-parent-action/changeparentpassword.ts
index 9450531..d13e48a 100644
--- a/src/function/sync/apply-actions/dispatch-parent-action/changeparentpassword.ts
+++ b/src/function/sync/apply-actions/dispatch-parent-action/changeparentpassword.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -15,7 +15,6 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import * as Sequelize from 'sequelize'
 import { ChangeParentPasswordAction, InvalidChangeParentPasswordIntegrityException } from '../../../../action/changeparentpassword'
 import { Cache } from '../cache'
 import { ApplyActionException } from '../exception/index'
@@ -31,8 +30,7 @@ export async function dispatchChangeParentPassword ({ action, cache }: {
       userId: action.parentUserId,
       type: 'parent'
     },
-    transaction: cache.transaction,
-    lock: Sequelize.Transaction.LOCK.UPDATE
+    transaction: cache.transaction
   })
 
   if (!parentEntry) {
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/removeuser.ts b/src/function/sync/apply-actions/dispatch-parent-action/removeuser.ts
index dc450ea..ad794b9 100644
--- a/src/function/sync/apply-actions/dispatch-parent-action/removeuser.ts
+++ b/src/function/sync/apply-actions/dispatch-parent-action/removeuser.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -106,8 +106,7 @@ export async function dispatchRemoveUser ({ action, cache, parentUserId }: {
         familyId: cache.familyId,
         childId: action.userId
       },
-      transaction: cache.transaction,
-      lock: Sequelize.Transaction.LOCK.UPDATE
+      transaction: cache.transaction
     })
 
     await cache.database.categoryApp.destroy({
diff --git a/src/function/sync/apply-actions/dispatch-parent-action/setchildpassword.ts b/src/function/sync/apply-actions/dispatch-parent-action/setchildpassword.ts
index 6e7e634..8ecada5 100644
--- a/src/function/sync/apply-actions/dispatch-parent-action/setchildpassword.ts
+++ b/src/function/sync/apply-actions/dispatch-parent-action/setchildpassword.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -15,7 +15,6 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import * as Sequelize from 'sequelize'
 import { SetChildPasswordAction } from '../../../../action'
 import { Cache } from '../cache'
 import { MissingUserException } from '../exception/missing-item'
@@ -30,8 +29,7 @@ export async function dispatchSetChildPassword ({ action, cache }: {
       userId: action.childUserId,
       type: 'child'
     },
-    transaction: cache.transaction,
-    lock: Sequelize.Transaction.LOCK.UPDATE
+    transaction: cache.transaction
   })
 
   if (!childEntry) {
diff --git a/src/worker/delete-deprecated-purchases.ts b/src/worker/delete-deprecated-purchases.ts
index ceb37b0..96851cd 100644
--- a/src/worker/delete-deprecated-purchases.ts
+++ b/src/worker/delete-deprecated-purchases.ts
@@ -1,6 +1,6 @@
 /*
  * server component for the TimeLimit App
- * Copyright (C) 2019 - 2020 Jonas Lochmann
+ * Copyright (C) 2019 - 2021 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
@@ -53,7 +53,6 @@ async function deleteDeprecatedPurchases ({ database, websocket }: {
       },
       attributes: ['familyId'],
       transaction,
-      lock: Sequelize.Transaction.LOCK.UPDATE,
       limit: 100
     })).map((item) => item.familyId)