Symptoms
When attempting to migrate an existing Lansweeper installation to a new server using the documented migration procedure, the installation fails during setup. Specifically, during a fresh installation on the new server, when selecting the Advanced installation option and configuring an existing SQL Server database, an error occurs after entering the SQL Server name and SQL authentication credentials. As a result, the installation cannot proceed, preventing completion of the migration to the new server.
Setup has detected that the specified SQL user does not have enough rights to install Lansweeper database.
A user with system administrator rights is required!
Checking rights for user: lansweeperuser … failed!

Diagnosis
This commonly occurs when customers try to use the "lansweeperuser" account to perform the installation, which does not have the required rights.
The user performing the database installation must be a member of your SQL Server's sysadmin server role.
Only when the installation has completed, the Lansweeper service and web console will connect to the database using a newly created SQL user called "lansweeperuser", which has access only to the Lansweeper database.
Solution
Rerun the Lansweeper installation on the new server and ensure that the SQL credentials used during setup belong to a SQL Server login that is a member of the sysadmin server role.
This can be an existing SQL administrator account or a temporary SQL login that has sysadmin rights. Use this account only for the duration of the installation when selecting the Advanced installation option and configuring the database connection.
Once the installation and database upgrade have completed successfully, Lansweeper will automatically create and use the lansweeperuser SQL login to connect to the database. No further sysadmin permissions are required after installation.
If needed, the temporary sysadmin account can be removed or its permissions reduced after the installation is complete.
Relevant KB articles