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Título
Error: Unable to cast object of type 'System.DBNull' to type 'System.String' -
Descripción
Error: Unable to cast object of type 'System.DBNull' to type 'System.String' when creating maintenance plan or job.
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Causa
SQL Server SERVERNAME may be NULL or not match the current Microsoft Windows NT machine name.
A few reasons why the SQL Server SERVERNAME may be NULL or not match the current Microsoft Windows NT machine name:
1. The computer was renamed.
2. An image was taken of the SQL Server computer, and then copied onto another computer.
3. The sp_dropserver stored procedure was run for the local SERVERNAME.
4. @@Servername of null can happen if there is no entry in sys.servers for server_id 0. check sys.servers with this: select * from sys.servers where server_id=0 -
Resolución
WORKAROUND:
sp_dropserver 'old_name'go
sp_addserver 'new_name', 'local'
goNote: After you run the sp_addserver stored procedure, you must restart the SQL Server service for the change to @@SERVERNAME to take effect.SQL Server Books Online also states the following: You do not have to run Setup again to reset the computer name.
The preceding statement is only true if it is not a virtual server. To rename a virtual server you DO have to uninstall, and then reinstall the virtual server.Note: Machine name and SQL Server name must be the same. If it is different, make the necessary changes in your DNS Server. Or make note in host file located in "C:\WINDOWS\system32\drivers\etc"