Question

About once a day or two now my web site starts throwing and error when people try to login and no one can log in until I restart IIS. How can Any() do this and what can I do to fix it?

Here’s the function throwing the exception:

        public override bool ValidateUser(string username, string password)
    {
        var db = Access.Context;
        var query =
            from p in db.Players
            where p.PlayerName == username
                && p.Password == password 
            select p
        ;
        return query.Any();
    }

Other LINQ to SQL queries work fine. Here’s the stack trace.

InvalidOperationException: Sequence contains no elements 

   System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) +1151
    System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) +113
    System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) +344
    System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute(Expression expression) +23
    System.Linq.Queryable.Any(IQueryable`1 source) +243
    FortyTwoAccess.PlayerProvider.ValidateUser(String username, String password) in C:\dev\FortyTwo\FortyTwoAccess\PlayerProvider.cs:114
    FortyTwoClient.Models.AccountMembershipService.ValidateUser(String userName, String password) in C:\dev\FortyTwo\FortyTwoClient\Models\AccountModels.cs:117
    FortyTwoClient.Controllers.AccountController.LogOn(LogOnModel model, String returnUrl) in C:\dev\FortyTwo\FortyTwoClient\Controllers\AccountController.cs:42
    lambda_method(Closure , ControllerBase , Object[] ) +157
    System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17

Answer 1

The fix for this was to not use a class variable to save the context and instead instantiate the context locally in each method wrapped in a using.