Unable to cast object of type 'System.DBNull' to type 'System.String'




Unable To Cast Object Of Type 'System.DBNull' To Type 'System.String', System.InvalidCastException, DBNULL, System.DBNULL, System.String, 'System.String', Unable To Cast Object, Typecast, DBNULL Check, Asp.Net, IIS

We get this error in the following situation. When database object returns NULL, "DBNULL", and we try to typecast the result.

Unable To Cast Object Of Type 'System.DBNull' To Type 'System.String', System.InvalidCastException, DBNULL, System.DBNULL, System.String, 'System.String', Unable To Cast Object, Typecast, DBNULL Check, Asp.Net, IIS

In the above example, you can see, the reader["name"] is returning NULL. When we try to typecast to string, we get this error.





Unable To Cast Object Of Type 'System.DBNull' To Type 'System.String', System.InvalidCastException, DBNULL, System.DBNULL, System.String, 'System.String', Unable To Cast Object, Typecast, DBNULL Check, Asp.Net, IIS

We should check whether the database object is NULL before typecasting. In the above code, we check whether reader["DBCOLUMN"] is NULL or not. After DBNULL check, we can typecast as per our requirement. By this way we can resolve this issue.