My application uses SSRS (on SQL Server 2017 on a server) and IIS. It runs fine in my IDE (VS 2017 or VS 2015) but when I put it on the server I get an error page.
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
No connection string to SQL Server Express.