Recently I have faced this issues, I have got an opportunity to provide some enhancements to existing application. When I start running the application, I got this error. After analyzing further with configuration, I found that the connection string is not well-formed in the web.config.
Solution:
Check your connection string. If you need help with it check Connection Strings, which has a list of commonly used ones.
Commonly used Connection Strings:
SQL Server 2012
Standard Security
Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;
Trusted Connection
Server=myServerAddress;Database=myDataBase;Trusted_Connection=True;
Connection to a SQL Server instance
The server/instance name syntax used in the server option is the same for all SQL Server connection strings.
Server=myServerName\myInstanceName;Database=myDataBase;User Id=myUsername;
Password=myPassword;
SQL Server 2005
Standard Security
Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;
Trusted Connection
Server=myServerAddress;Database=myDataBase;Trusted_Connection=True;
Connection to a SQL Server instance
The server/instance name syntax used in the server option is the same for all SQL Server connection strings.
Server=myServerName\myInstanceName;Database=myDataBase;User Id=myUsername;Password=myPassword;
MySQL
Standard
Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;
Specifying TCP port
Server=myServerAddress;Port=1234;Database=myDataBase;Uid=myUsername;Pwd=myPassword;
Oracle
Using TNS
Data Source=TORCL;User Id=myUsername;Password=myPassword;
Using integrated security
Data Source=TORCL;Integrated Security=SSPI;
