SQL Server: Object Validation Error by Estimated Plan While Actual Plan Working Fine

It happened dozen of times when I tried to get an Estimated Execution Plan, it return object verification error, while the same Stored Procedure was working perfectly. Then what’s wrong with Estimated Execution Plan, lets create a simple procedure.

CREATE PROCEDURE Proc_TestProcedure

AS
BEGIN
      IF 1 = 2
            SELECT * FROM NoTable -- NoTable doesn't exists
      ELSE
      SELECT 'ESLE'
END
GO

On compilation and execution, above stored procedure will not return any error, because condition is never true, so it never need to exec SELECT * FROM NoTable, and to check that table exists or not. Now just try to get execution plan of

EXEC Proc_TestProcedure

It will return error.

Msg 208, Level 16, State 1, Procedure Proc_TestProcedure, Line 8

Invalid object name 'NoTable'.

Why So.

Because on estimation, query optimizer check each and every statement separately and once it try to estimate cost for “NoTable”, which never exists, it returns above mentioned error.