SQL Server error when connecting or trying to set up configuration database

While configuring your Enterprise Configuration database on SQL Server you might see error such as "Access is denied", or "A network-related or instance-specific error occurred while establishing a connection to SQL Server. The Server was not found or was not accessible..." This means there is something blocking the connection attempt, either by protocol setup or user access.

Solutions

1. Ensure the user access is properly configured.

   For example, you could have some kind of SQL access issue with the running user of the specific SQL service or any SQL folder permissions defined for the running user of the SQL services.

2. Try enabling the TCP protocol from “SQL Server Configuration Manager” tool.

   Learn more about this solution in this Stack Overflow article.