‘DropdownList’ has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value

The problem here is that when the data binding is performed on the dropdownlist the selectedValue for items has extraneous trailing whitespaces.

Many programmers make the mistake of assuming that the trailing whitespace is due to the width of the sql nchar column (Sorry guys reducing the width won’t do much good)

First letme give you the solution, later at the end of this post ill give you a probable reason that i have discovered so as to to why this anomally occurs.

Solution.

Trim the selectedValues on the databound event of the dropdownlist as shown in the following code

        {

For absolute beginners: Make sure the above funtion is added as an event handler for the databound event of the dropdownlist

and voila!!! problem solved , Party!!!!!  (Atleast in my case he he..)

Hope this helps,

drop me a mail at bodani.pankaj@live.com and send your code if this doesnt work for you.

The actual problem is here: I found this on MSDN

“In order to translate data between the object model and the database, a type mapping must be defined. LINQ to SQL uses a type mapping to match each common language runtime (CLR) type with a particular SQL Server type. You can define type mappings and other mapping information, such as database structure and table relationships, inside the object model with attribute-based mapping. Alternatively, you can specify the mapping information outside the object model with an external mapping file”

this may even happen if you are using other type of data sources such a SQLDatasource

{