Troubleshooting Exceptions: System.Collections.Generic.KeyNotFoundException 

A KeyNotFoundException is thrown when an attempt is made to retrieve a key or key value pair from a collection using a nonexistent key.

Associated Tips

• Check that the key you are using exists in the collection you are attempting to access.
  This exception occurs when an operation attempts to retrieve an element in a collection using a key that does not exist in that collection.

Remarks

The ContainsKey method can be used to determine whether a key exists.

See Also

Tasks

How to: Find Out More About an Exception with the Exception Assistant

Reference

System.Collections.Generic
KeyNotFoundException