ADF not connecting Azure SQL

your setup seems correct at the SQL and service principal level, the connection is failing because ADF cannot reach the SQL server network endpoint. Since you are using a Managed VNet IR, ensure the SQL Server has either public access enabled with allow Azure Services turned on, or a private endpoint from ADF created and approved. If using private endpoint, verify its status is Approved and that a Private DNS Zone privatelink.database.windows.net is linked to the Managed VNet. Until the network path is open, ADF will not be able to resolve the server name and the connection will fail, regardless of credentials.