Isssue "Key Not Found in Dictionnary"

[ynyonato]

I'm trying to insert 5000+ rows from a datatable to SQL server Database.
Every time i invoke db.BulkInsert(resList); error message is the one mentioned in object.
(db is my context name, and resList is a List of entity i wanted to insert).

My Primary Key is generated through my code and might be inserted that way with all the rows.
Can you please help !!!

Thanks in advance