Question: What may be a cause of the error shown below. The user running the code below is a member of db_securityadmin database role:

ALTER SERVER ROLE db_ddladmin ADD MEMBER [myDomainName.com\Juan]

Msg 15151, Level 16, State 1, Line 3 Cannot add the principal 'myDomainName.com\Juan', because it does not exist or you do not have permission.

Remark: User [email protected] does exist and can login to his laptop as [email protected]. The following code also gives the same error:

ALTER SERVER ROLE db_ddladmin ADD MEMBER [[email protected]]

Ref: Add a member to a fixed server role

  • 1
    "User [email protected] does exists and can login to his laptop as [email protected]." can that user login to SQL Server using SSMS?
    – Ronaldo
    Commented Sep 30, 2022 at 20:16
  • @Ronaldo Your comment helped me resolved the issue (thank you). [email protected] exists in the Security\logins folder of SQL Managed Instance. But, we missed the following step in current db first: CREATE USER [[email protected]] FROM LOGIN [[email protected]]. Afterwards, the issue was resolved. For benefits of other users, if you like, you can explain the process in a bit more details - and I'll mark it as an Answer.
    – nam
    Commented Sep 30, 2022 at 21:16

1 Answer 1


Before making a user member of Server-level roles or Database-level roles it is important to make sure the login/user is already among the Principals listed on the instance and database.

  1. Check if the [email protected] login (or a Windows group of which it is a member) exists on the instance: Security > Logins. If it's not, run a CREATE LOGIN command;
  2. Check if there's a user created on the database associated to that login: Databases > YouDataBase > Security > Users. If you can't find one, create it with the CREATE USER command.

A very practical way to verify that in your case is to test if [email protected] can login and navigate to the database you'll be giving permissions using SSMS.

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