实体Framewok-基础提供程序在打开时失败-SQL

Question

I have two small web pages for a proyect in a server, they were working with no problems, but suddenly when I entered my login and password, I got an error message "The underlying provider failed on Open".

I edited the code so I can get the Inner Exception Message which was "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: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)".

When I run the application within Visual Studio, using the servers connection string, everything works correctly, and I even can access the database from other applications in another server, so SQL is accepting remote connections.

The problem is that I cant access the database from the applications that are in the same server as my SQL database. This is a new issue, as they have been running for months and they suddenly marked this error today.

Answer 1

In Visual Studio, unless you have an explicit SQL User Name and password in the connection string, the connection will be as you. Under IIS it will be as the IIS worker process. Assuming you're using integrated security, your app then wouldn't be able to connect to the database unless the IIS AppPool Identity is a user with access to the database on SQL Server. In this case, the fix is to create an SQL account for the site to use with the least privileges required for the site to work and put those in your connection string.

Alternatively, it may be that certain protocols are not configured (named pipes, remote connection etc.) in the SQL Server surface area configuration.