Cannot update identity column '%1!'.

Error Message:
Msg 8102, Level 16, State 1, Line 2
Cannot update identity column '%1!'.

Severity level:
16.

Description:
This error message appears, when you try to UPDATE one or more rows of a column on which the IDENTITY property has been defined

Consequences:
The T-SQL statement can be parsed, but causes the error at runtime.

Resolution:
Error of the Severity level 16 are generated by the user and are corrigible by the user. In this case all columns over which the PRIMARY KEY constraint should be declared needs to be explicitly created as NOT NULL.

Versions:
All versions of SQL Server.

Example(s):
USE tempDB
GO
CREATE TABLE #t
(
 c1 INT IDENTITY
)
GO
INSERT INTO #t DEFAULT VALUES
UPDATE #t SET c1 = 2
SELECT *
FROM #t
DROP TABLE #t

Remarks:
In the above example, we try to UPDATE column c1 of the table #t. Because the IDENTITY property has been created for this column, the UPDATE statement fails. There is a workaround to the effect that you have modified values in those columns afterwards, but that workaround requires several steps and might not applicable to every environment. You should carefully evaluate benefit and cost before you go for this workaround.