Format exception for LINQ to sql. String must be exactly one character long

This code throws an error "Format exception. String must be exactly one character long". I cant see why. Any ideas?

var contract = (from c in db.SM_CONTRACTs
                where c.CON_TUK2 != null
                   && c.CON_TUK2 == req.Imei
                select c).FirstOrDefault();

req.Imei looks like "8944200005977030038"

The data context loooks like:

[Column(Storage="_CON_TUK2", DbType="VarChar(20)")]
public string CON_TUK2
{
    get
    {
        return this._CON_TUK2;
    }
    set
    {
        if ((this._CON_TUK2 != value))
        {
            this.OnCON_TUK2Changing(value);
        开发者_如何转开发    this.SendPropertyChanging();
            this._CON_TUK2 = value;
            this.SendPropertyChanged("CON_TUK2");
            this.OnCON_TUK2Changed();
        }
    }
}

What is probably going on is that the SM_CONTRACTs table in your database has one or more varchar(1) (or nvarchar(1)) columns. The Code Generator will convert this to System.Char in your model. This will throw the FormatException whenever the data is not exactly one character.

Try to look for this column in your model designer and change the Code Generation - Type property to 'String'.

It has not necessarily to do with a field that you use in your specific linq query (or within your where statement)!

It could be ANY of your models fields that is a CHAR(1) but has an "empty string" as data stored. Which is valid for an sql CHAR type, but not for System.Char in C#.

Changing this fields type to string should be the easy fix.