IDENTITY_INSERT is set to OFF - How to turn it ON?

Should you instead be setting the identity insert to on within the stored procedure? It looks like you're setting it to on only when changing the stored procedure, not when actually calling it. Try:

ALTER procedure [dbo].[spInsertDeletedIntoTBLContent]
@ContentID int, 

SET IDENTITY_INSERT tbl_content ON

...insert command...

SET IDENTITY_INSERT tbl_content OFF
GO

I believe it needs to be done in a single query batch. Basically, the GO statements are breaking your commands into multiple batches and that is causing the issue. Change it to this:

SET IDENTITY_INSERT tbl_content ON
/* GO */

...insert command...

SET IDENTITY_INSERT tbl_content OFF
GO

Shouldn't you be setting identity_Insert ON, inserting the records and then turning it back off?

Like this:

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
SET IDENTITY_INSERT tbl_content ON
GO

ALTER procedure [dbo].[spInsertDeletedIntoTBLContent]
@ContentID int, 
SET IDENTITY_INSERT tbl_content ON
...insert command...
SET IDENTITY_INSERT tbl_content OFF

Reminder

SQL Server only allows one table to have IDENTITY_INSERT property set to ON.

This does not work:

SET IDENTITY_INSERT TableA ON
SET IDENTITY_INSERT TableB ON
... INSERT ON TableA ...
... INSERT ON TableB ...
SET IDENTITY_INSERT TableA OFF
SET IDENTITY_INSERT TableB OFF

Instead:

SET IDENTITY_INSERT TableA ON
... INSERT ON TableA ...
SET IDENTITY_INSERT TableA OFF
SET IDENTITY_INSERT TableB ON
... INSERT ON TableB ...
SET IDENTITY_INSERT TableB OFF

Add this line above you Query

SET IDENTITY_INSERT tbl_content ON

The Reference: http://technet.microsoft.com/en-us/library/aa259221%28v=sql.80%29.aspx

My table is named Genre with the 3 columns of Id, Name and SortOrder

The code that I used is as:

SET IDENTITY_INSERT Genre ON

INSERT INTO Genre(Id, Name, SortOrder)VALUES (12,'Moody Blues', 20) 

Add set off also

 SET IDENTITY_INSERT Genre ON

    INSERT INTO Genre(Id, Name, SortOrder)VALUES (12,'Moody Blues', 20) 

    SET IDENTITY_INSERT Genre  OFF

I had two different tables and for the first one insert works fine but for the second one throws this exception regarding Identity Insert. The issue was that the table had a field(int) as a forgery key which wasn't populated.