Столбец конфликтует с типом других столбцов в несводном списке

Я превращаю sys.[views]в пары ключ-значение для сравнения со значениями на другом сервере для проверки согласованности. Я столкнулся с проблемой, которая возвращает ошибку.

Сообщение 8167, уровень 16, состояние 1, строка 51

Тип столбца "type" конфликтует с типом других столбцов, указанных в списке UNPIVOT.

Запрос:

SELECT
sourceUnpivoted.idServer,
sourceUnpivoted.sourceServerName,
sourceUnpivoted.name,
sourceUnpivoted.columnName,
sourceUnpivoted.columnValue
FROM (
SELECT 
CAST('1' AS VARCHAR(255)) AS idServer,
CAST('thisOne' AS VARCHAR(255)) AS sourceServerName,
CAST('theDatabase' AS VARCHAR(255)) AS sourceDatabaseName,
CAST(name AS VARCHAR(255)) AS name,
CAST(object_id AS VARCHAR(255)) AS object_id,
CAST(principal_id AS VARCHAR(255)) AS principal_id,
CAST(schema_id AS VARCHAR(255)) AS schema_id,
CAST(parent_object_id AS VARCHAR(255)) AS parent_object_id,
CAST(type AS VARCHAR(255)) AS type,
CAST(type_desc AS VARCHAR(255)) AS type_desc,
CAST(create_date AS VARCHAR(255)) AS create_date,
CAST(lock_escalation_desc AS VARCHAR(255)) AS lock_escalation_desc
...
FROM noc_test.dbo.stage_sysTables
) AS databaseTables
UNPIVOT (
columnValue FOR columnName IN (
object_id,
principal_id,
schema_id,
parent_object_id,
type,
type_desc,
create_date,
lock_escalation_desc
) 
) AS sourceUnpivoted

Почему это не нравится [type], [type_desc], [lock_escalation_desc]??? Я также пробовал CONVERT(VARCHAR(255),type) AS type