C# application stopped working for no reason without any changes in code or configuration

Question

So something very strange happened with this old C# application I started to work on. I copied it locally and I've been studying the codebase without making any changes. In fact, it ran locally every day for the past week. Again, no code changes or changing in the configuration, etc. Today, I wasn't able to run it anymore. I even cloned a fresh copy - no luck. Now it's giving me this error and I don't know why. The database is remote but I can see that it's working when RDPing. What could cause this?

public static SqlConnection OpenSqlConnection(dbConnections connection, string applicationName = null)
        {
            var conn = CreateSqlConnection(connection, applicationName);
            conn.Open();
            return conn;
        }

In this line, I get the following error:

System.Data.SqlClient.SqlException: '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)'

Does this answer your question? [Why am I getting "Cannot Connect to Server - A network-related or instance-specific error"?](https://stackoverflow.com/questions/18060667/why-am-i-getting-cannot-connect-to-server-a-network-related-or-instance-speci) — Tom Joney, Jul 16 '20 at 21:38
What method are you using to connect, TCP, host names etc? Can you show your connection string (obviously remove any sensitive data!) — Charleh, Jul 16 '20 at 21:56

score 1 · Answer 1 · answered Jul 16 '20 at 21:39

1

This Definitely looks like a network issue rather than anything to do with the code. Check if Your SQL Server is accessible over the network

answered Jul 16 '20 at 21:39

Vivek Srivastava

197
5

1

I was thinking about that too. I checked the database on the remote machine and I was able to connect. I also added it in the Visual Studio Database explorer and was able to connect just fine. What else should I do ? – crytodactyl Jul 16 '20 at 21:40
Visual Studio Database explorer on the same machine where your code is available? – Vivek Srivastava Jul 16 '20 at 21:42
No, that's a good idea. But why would it stop working on my local machine after weeks of running just fine ? – crytodactyl Jul 16 '20 at 21:42
system updates or firewall updates can be blamed :) – Vivek Srivastava Jul 16 '20 at 21:47

C# application stopped working for no reason without any changes in code or configuration

1 Answers1