Sitecore 10.1 install error: sql 'securityuser' already exists in the current database

Question

Error

When installing Sitecore 10.1, I'm getting the below error.

[WebDeploy]:[Path] C:\Program Files\iis\Microsoft Web Deploy V3\msdeploy.exe
Error Code: ERROR_SQL_EXECUTION_FAILURE
More Information: An error occurred during execution of the database script. The error occurred between the following lines of the script: "18" and "21". The verbose log might have more information about the error. The command started with the following:

"CREATE USER [securityuser] WITH PASSWORD = 'PvdT"
User, group, or role 'securityuser' already exists in the current database. https://go.microsoft.com/fwlink/?LinkId=178587 Learn more at: https://go.microsoft.com/fwlink/?LinkId=221672#ERROR_SQL_EXECUTION_FAILURE.

Error: User, group, or role 'securityuser' already exists in the current database.
Error count: 1.

Anyone have any ideas what this could be? Scouring the web with no luck yet.

Note

Creates the majority of the required databases and all of the databases have the securityuser already created inside of them. Makes me think the SIF is creating the user, and then trying to create it again in the same db?

Things tried

• deleting existing sql global securityuser
• looked for existing global sql roles named securityuser, didn't see any
• restarting sql server
• deleting all db's and running SIF again
• verified webdeploy is installed, have both 3.5 & 3.6
• verified SQL Server 2017 prerequisite installed

Answer 1

Unless your SIF tasks have been customized or modified, they are not expected to create the securityuser database user twice in the Core database. The fact that the securityuser exists in all your databases seems to indicate that it is a SQL Server login user and not a database user.

If you are not able to identify the reason behind the preexistence of this user, you should be able to avoid this installation error using a different name for the Security DB user name, editing the default value of the SqlSecurityUser parameter. This parameter is not exposed in the json configurations for the different topologies, so it might be easier to just edit its default value directly in the XP0-sitecore.json file, where it is defined.

This is the definition of the parameter to look for and to edit its default value (ie. sitecoresecurityuser):

"SqlSecurityUser": {
            "Type": "string",
            "DefaultValue": "sitecoresecurityuser",
            "Description": "The Sql user for the Security connection string in Sitecore."
        }