entity framework - Getting a 'System.InvalidOperationException' when changing the connection string for connecting to a database C# -

i getting unhandled exception of type 'system.invalidoperationexception' occurred in entityframework.dll when run application.

my application basic c# application using entity framework code first approach , trying connect database.

the following code used add data database (which worked before added connection string app.config file.

static void main(string[] args)     {         using (var context = new behaviourcontext())         {             behaviour behaviour = new behaviour()             {                 name = "test behaviour",                 activation_threshold = 90,                 currently_executing = false,                 preconditions_met = false,                 priority = 0.9f             };             context.behaviours.add(behaviour);             context.savechanges();         }     } 

this context class:

public class behaviourcontext: dbcontext {     public behaviourcontext(): base("name=behaviourconnectionstring")     {      }     public dbset<behaviour> behaviours { get; set; } } 

this working fine until added connection string:

<connectionstrings> <add name="behaviourconnectionstring" connectionstring="data source=.;initial catalog=behaviourdb-byconnectionstring;integrated security=true" providername="system.data.sqlclient"/> 

and full error when run application:

an unhandled exception of type 'system.invalidoperationexception' occurred in entityframework.dll

additional information: context cannot used while model being created. exception may thrown if context used inside onmodelcreating method or if same context instance accessed multiple threads concurrently. note instance members of dbcontext , related classes not guaranteed thread safe.

any help, hints or tip appreciated. :)

solved

there error in connection sting, had forgotten add '\sqlexpress'

<connectionstrings> <add name="behaviourconnectionstring" connectionstring="data source=.\sqlexpress;initial catalog=behaviourdb-byconnectionstring;integrated security=true" providername="system.data.sqlclient"/> 

.