How to generate and manually insert a uniqueidentifier in sql server?

ApplicationId must be of type UniqueIdentifier. Your code works fine if you do:

DECLARE @TTEST TABLE
(
  TEST UNIQUEIDENTIFIER
)

DECLARE @UNIQUEX UNIQUEIDENTIFIER
SET @UNIQUEX = NEWID();

INSERT INTO @TTEST
(TEST)
VALUES
(@UNIQUEX);

SELECT * FROM @TTEST

Therefore I would say it is safe to assume that ApplicationId is not the correct data type.

Kindly check Column ApplicationId datatype in Table aspnet_Users , ApplicationId column datatype should be uniqueidentifier .

*Your parameter order is passed wrongly , Parameter @id should be passed as first argument, but in your script it is placed in second argument..*

So error is raised..

Please refere sample script:

DECLARE @id uniqueidentifier
SET @id = NEWID()
Create Table #temp1(AppId uniqueidentifier)

insert into #temp1 values(@id)

Select * from #temp1

Drop Table #temp1