Format of the initialization string does not conform to specification starting at index 0. 
 
                             Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 
 
              Exception Details: System.ArgumentException: Format of the initialization string does not conform to specification starting at index 0.
 
             Source Error: 
 
                                                                        An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.                                                               
             Stack Trace: 
 
                                                                       [ArgumentException: Format of the initialization string does not conform to specification starting at index 0.]
   System.Data.Common.DbConnectionOptions.GetKeyValuePair(String connectionString, Int32 currentPosition, StringBuilder buffer, Boolean useOdbcRules, String& keyname, String& keyvalue) +1284
   System.Data.Common.DbConnectionOptions.ParseInternal(Hashtable parsetable, String connectionString, Boolean buildChain, Hashtable synonyms, Boolean firstKey) +115
   System.Data.Common.DbConnectionOptions..ctor(String connectionString, Hashtable synonyms, Boolean useOdbcRules) +99
   System.Data.SqlClient.SqlConnectionString..ctor(String connectionString) +52
   System.Data.SqlClient.SqlConnectionFactory.CreateConnectionOptions(String connectionString, DbConnectionOptions previous) +25
   System.Data.ProviderBase.DbConnectionFactory.GetConnectionPoolGroup(String connectionString, DbConnectionPoolGroupOptions poolOptions, DbConnectionOptions& userConnectionOptions) +141
   System.Data.SqlClient.SqlConnection.ConnectionString_Set(String value) +38
   System.Data.SqlClient.SqlConnection.set_ConnectionString(String value) +4
   System.Web.UI.WebControls.SqlDataSourceView.ExecuteSelect(DataSourceSelectArguments arguments) +128
   System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +13
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +140
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +68
   System.Web.UI.WebControls.GridView.DataBind() +5
   System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +61
   System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls() +67
   System.Web.UI.Control.EnsureChildControls() +97
   System.Web.UI.Control.PreRenderRecursiveInternal() +50
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5729

Data Source=SERVERNAME;Initial Catalog=DATABASENAME;UID=USERNAME;PWD=PASSWORD

connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Ratios.mdf;Integrated Security=True;User Instance=True"

connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=Ratios;Integrated Security=True;User Instance=True"