An explicit value for the identity column in table can only be specified when a column list is used and IDENTITY_INSERT is ON
If you run into the following error message:
An explicit value for the identity column in table ‘<TABLE_NAME>’ can only be specified when a column list is used and IDENTITY_INSERT is ON.
It can mean two things.
One you’ve not enabled identity insert on your table, meaning SQL Server will not let you insert into the Identity column.
This can be rectified with the following statement:
SET IDENTITY_INSERT table_name ON
And then turn it off again when done
SET IDENTITY_INSERT table_name OFF
However it can also mean that you are using for example INSERT INTO, in which cause the message tells you to specify the column names. This means using the following syntax:
INSERT INTO target_able_name (column_name1, column_name2…. column_nameN)
SELECT
YOUR_SELECT_LIST_WHICH_MATCHES_COLUMN_LIST
FROM source_table_name
I wasn’t aware of the latter syntax myself before I got the error message today. But then I learned a little something new today after all 
