One of our VS .NET 2008 windows forms applications runs from multiple client machines. The application randomly has login failures from random machines and from random places in the code. The login works almost every time but about once every fifteen minutes an error shows up in SQL Server error logs from a random user. We are running a clustered SQL Server 2005 system and the database is in 2005 (90) mode.
The following error appears in the SQL Server error logs:
Login failed for 'App_Login'. [CLIENT: XXX.XXX.X.XXX] Error: 18456, Severity: 14, State: 16.
The following error is what the client sees:
System.Data.SqlClient.SqlException: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
The connection string used by the application is:
Data Source=XX.XXX.XXX.XXX;Network Library=DBMSSOCN;Initial Catalog=document7;User Id=App_Login;Password=PASSWORDHERE;
(NOTE: XXX.XXX.X.XXX and XX.XXX.XXX.XXX are the IP Addresses)
- The 'document7' and 'master' databases are in multi-user mode.
- The login has access to 'document7' and to 'master'.
- The clients sometimes run into the error but retrying the same action after a failure is successful without any changes.
- I am able to use 'App_Login' using the management studio without problems. I can access the 'document7' database and the 'master' database without problems.
- We have other applications that use the same connection string and have no problems.
- I have tried the login with a default database of 'master' and 'document7' with the same result in both cases.
Thank you for your time and any assistance!