During a logon process to SQL server with SQL credentials the following error may appear: "Login failed for user 'username'. The user is not associated with a trusted SQL Server connection. (Microsoft SQL Server, Error: 18452)".  See screenshot below:

 

When logging into SCTM it gives error - "Login invalid".

This occurs when the SQL server has been configured to operate in "Windows Authentication Mode (Windows Authentication)" and doesn't allow the use of SQL accounts.  SCTM only supports users with SQL credentials.

To resolve this you must change the Authentication Mode of the SQL server from "Windows Authentication Mode (Windows Authentication)"  to "Mixed Mode (Windows Authentication and SQL Server Authentication)".

To change security authentication mode follow the steps below:

1.  In SQL Server Management Studio Object Explorer, right-click the server, and then click Properties.

2.  On the Security page, under Server authentication, select the new server authentication mode, and then click OK.

3.  In the SQL Server Management Studio dialog box, click OK to acknowledge the requirement to restart SQL Server.