How to fix the 15151 error on the SQL server? Bobcares, as a part of our Server Management Services offers solutions to every query that comes our way.

15151 error on the SQL server

A login is a security principal or an object that a secure system may authenticate. In order to connect to SQL Server, users must log in. You have the option of creating a login based on a Windows principal (such as a domain user or a Windows domain group) or one that is not (such as an SQL Server login).

A user is a database security principle. To connect to a database, there is a need to map logins to a database user. A login maps to several databases as distinct users, but it can only map as one user in each database. A user without a login can be generated in a partially contained database. By enabling a database’s guest user, a login that doesn’t map to a database user can access the database as the visitor user.

Logins are not the same as database users. In a separate step, we must map logins or Windows groups to database users or roles. Then we should provide users or roles permission to view database items.

Case 1

Error:

Msg 15151, Level 16, State 1, Line 2 Cannot alter the login ‘sa’, because it does not exist or you do not have permission.

Solution:

This mistake occurred due to a lack of rights. SA stands for system administrator and is the highest level of user in the system. If a user needs to change SA’s permissions, that user must have higher or comparable rights as the SA user.

Only users in the systemadmin group have the ability to change the rights of the SA user. By first adding any user to the systemadmin role and then using the same account to modify the system admin’s tool, we can fix the problem.

Case 2

Error:

Msg 15151, Cannot alter the user ‘xxxx’, because it does not exist or you do not have permission

Solution:

We need to create the user (CREATE USER [xxxx]) before we try to alter it. Missing the “create user” instruction before the alter may show the error. Login gets user entry to the server Database and the User gets user entry to a particular database. So in the script, we have to include create user from login.

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Conclusion

In this article, we have provided a general idea from our Tech team regarding the 15151 error along with a discussion on two use cases and its solution.