>>May be there are some test tables in that database.
>>
>>The simple way to check if the problem is in the table names
>>

>>select Table_Name from Information_Schema.Columns -- for this database

>>
>>see if there is something odd here
>>
>>Then check the same for constraints.
>
>Yes, I was able to simulate it on a table name which is a reserved name on the test server. Then, with the [] characters, it worked.

Add quotename for the constraint name as well. I always use quotename in my code.