diff --git a/backend/src/apis/humhub/model/Account.ts b/backend/src/apis/humhub/model/Account.ts
index 1eb3e37be..ac80a195b 100644
--- a/backend/src/apis/humhub/model/Account.ts
+++ b/backend/src/apis/humhub/model/Account.ts
@@ -3,12 +3,11 @@ import { User } from '@entity/User'
 
 import { convertGradidoLanguageToHumhub } from '@/apis/humhub/convertLanguage'
 import { PublishNameLogic } from '@/data/PublishName.logic'
-import { PublishNameType } from '@/graphql/enum/PublishNameType'
 
 export class Account {
   public constructor(user: User) {
     const publishNameLogic = new PublishNameLogic(user)
-    this.username = publishNameLogic.getUsername(user.humhubPublishName as PublishNameType)
+    this.username = publishNameLogic.getUsername()
     this.email = user.emailContact.email
     this.language = convertGradidoLanguageToHumhub(user.language)
     this.status = 1
diff --git a/backend/src/data/PublishName.logic.ts b/backend/src/data/PublishName.logic.ts
index d3643d633..3c89fc057 100644
--- a/backend/src/data/PublishName.logic.ts
+++ b/backend/src/data/PublishName.logic.ts
@@ -66,7 +66,8 @@ export class PublishNameLogic {
    * @returns user.alias for publishNameType = PUBLISH_NAME_ALIAS_OR_INITALS and user has alias
    *   else return user.firstName[0,2] + user.lastName[0,2] for publishNameType = [PUBLISH_NAME_ALIAS_OR_INITALS, PUBLISH_NAME_INITIALS]
    */
-  public getUsername(publishNameType: PublishNameType): string {
+  public getUsername(): string {
+    const publishNameType = this.user.humhubPublishName as PublishNameType
     if (
       [
         PublishNameType.PUBLISH_NAME_ALIAS_OR_INITALS,
diff --git a/backend/src/graphql/resolver/UserResolver.ts b/backend/src/graphql/resolver/UserResolver.ts
index e31dc4867..e74ae8f45 100644
--- a/backend/src/graphql/resolver/UserResolver.ts
+++ b/backend/src/graphql/resolver/UserResolver.ts
@@ -60,7 +60,6 @@ import {
   EVENT_ADMIN_USER_DELETE,
   EVENT_ADMIN_USER_UNDELETE,
 } from '@/event/Events'
-import { PublishNameType } from '@/graphql/enum/PublishNameType'
 import { isValidPassword } from '@/password/EncryptorUtils'
 import { encryptPassword, verifyPassword } from '@/password/PasswordEncryptor'
 import { Context, getUser, getClientTimezoneOffset } from '@/server/context'
@@ -172,7 +171,7 @@ export class UserResolver {
     if (CONFIG.HUMHUB_ACTIVE && dbUser.humhubAllowed) {
       const publishNameLogic = new PublishNameLogic(dbUser)
       humhubUserPromise = HumHubClient.getInstance()?.userByUsernameAsync(
-        publishNameLogic.getUsername(dbUser.humhubPublishName as PublishNameType),
+        publishNameLogic.getUsername(),
       )
     }
 
@@ -316,6 +315,8 @@ export class UserResolver {
     dbUser.firstName = firstName
     dbUser.lastName = lastName
     dbUser.language = language
+    // enable humhub from now on for new user
+    dbUser.humhubAllowed = true
     if (alias && (await validateAlias(alias))) {
       dbUser.alias = alias
     }
@@ -386,6 +387,9 @@ export class UserResolver {
       await queryRunner.release()
     }
     logger.info('createUser() successful...')
+    if (CONFIG.HUMHUB_ACTIVE) {
+      void syncHumhub(null, dbUser)
+    }
 
     if (redeemCode) {
       eventRegisterRedeem.affectedUser = dbUser
@@ -736,7 +740,8 @@ export class UserResolver {
     if (!humhubClient) {
       throw new LogError('cannot create humhub client')
     }
-    const username = dbUser.alias ?? dbUser.gradidoID
+    const userNameLogic = new PublishNameLogic(dbUser)
+    const username = userNameLogic.getUsername()
     let humhubUser = await humhubClient.userByUsername(username)
     if (!humhubUser) {
       humhubUser = await humhubClient.userByEmail(dbUser.emailContact.email)
diff --git a/backend/src/graphql/resolver/util/syncHumhub.ts b/backend/src/graphql/resolver/util/syncHumhub.ts
index 426f89c92..c229df655 100644
--- a/backend/src/graphql/resolver/util/syncHumhub.ts
+++ b/backend/src/graphql/resolver/util/syncHumhub.ts
@@ -7,11 +7,12 @@ import { UpdateUserInfosArgs } from '@/graphql/arg/UpdateUserInfosArgs'
 import { backendLogger as logger } from '@/server/logger'
 
 export async function syncHumhub(
-  updateUserInfosArg: UpdateUserInfosArgs,
+  updateUserInfosArg: UpdateUserInfosArgs | null,
   user: User,
 ): Promise<void> {
   // check for humhub relevant changes
   if (
+    updateUserInfosArg &&
     updateUserInfosArg.alias === undefined &&
     updateUserInfosArg.firstName === undefined &&
     updateUserInfosArg.lastName === undefined &&