diff --git a/src/auth/auth.service.ts b/src/auth/auth.service.ts
index 0439686bc..e078064de 100644
--- a/src/auth/auth.service.ts
+++ b/src/auth/auth.service.ts
@@ -117,7 +117,9 @@ export class AuthService {
         new Date(validUntil),
       );
     }
-    const createdToken = await this.authTokenRepository.save(token);
+    const createdToken = (await this.authTokenRepository.save(
+      token,
+    )) as AuthToken;
     return this.toAuthTokenWithSecretDto(createdToken, `${keyId}.${secret}`);
   }
 
@@ -150,7 +152,7 @@ export class AuthService {
     ) {
       // tokens validUntil Date lies in the past
       throw new TokenNotValidError(
-        `AuthToken '${token}' is not valid since ${accessToken.validUntil}.`,
+        `AuthToken '${token}' is not valid since ${accessToken.validUntil.toISOString()}.`,
       );
     }
     return accessToken;
@@ -173,7 +175,10 @@ export class AuthService {
 
   toAuthTokenDto(authToken: AuthToken): AuthTokenDto | null {
     if (!authToken) {
-      this.logger.warn(`Recieved ${authToken} argument!`, 'toAuthTokenDto');
+      this.logger.warn(
+        `Recieved ${String(authToken)} argument!`,
+        'toAuthTokenDto',
+      );
       return null;
     }
     const tokenDto: AuthTokenDto = {
diff --git a/src/groups/groups.service.ts b/src/groups/groups.service.ts
index 042ef0996..ea2e7fd0d 100644
--- a/src/groups/groups.service.ts
+++ b/src/groups/groups.service.ts
@@ -45,7 +45,7 @@ export class GroupsService {
    */
   toGroupDto(group: Group | null | undefined): GroupInfoDto | null {
     if (!group) {
-      this.logger.warn(`Recieved ${group} argument!`, 'toGroupDto');
+      this.logger.warn(`Recieved ${String(group)} argument!`, 'toGroupDto');
       return null;
     }
     return {
diff --git a/src/notes/notes.service.ts b/src/notes/notes.service.ts
index 42ac32bd0..0ff2e7112 100644
--- a/src/notes/notes.service.ts
+++ b/src/notes/notes.service.ts
@@ -299,7 +299,7 @@ export class NotesService {
    * @param {Note} note - the note to use
    * @return {NotePermissionsDto} the built NotePermissionDto
    */
-  toNotePermissionsDto(note: Note): Promise<NotePermissionsDto> {
+  toNotePermissionsDto(note: Note): NotePermissionsDto {
     return {
       owner: this.usersService.toUserDto(note.owner),
       sharedToUsers: note.userPermissions.map((noteUserPermission) => ({
diff --git a/src/users/users.service.ts b/src/users/users.service.ts
index b29b0e30e..814743b95 100644
--- a/src/users/users.service.ts
+++ b/src/users/users.service.ts
@@ -56,7 +56,7 @@ export class UsersService {
 
   toUserDto(user: User | null | undefined): UserInfoDto | null {
     if (!user) {
-      this.logger.warn(`Recieved ${user} argument!`, 'toUserDto');
+      this.logger.warn(`Recieved ${String(user)} argument!`, 'toUserDto');
       return null;
     }
     return {