Since this is a backup you are trying to run, here is another option:

declare @dbname varchar(128),

@filedate varchar(64);

declare @diskfile varchar(256) = 'H:\Preupgrade\Backups\' + @dbname + '_' + @filedate;

declare @filename varchar(256) = @dbname + @filedate;

declare @SQLCmd varchar(max) =

'BACKUP DATABASE @dbname

TO DISK = @diskfile

WITH NOFORMAT,

NAME = @filename,

SKIP,

REWIND,

NOUNLOAD,

STATS = 10;';

declare @params @varchar(max) = '@dbname varchar(128), @diskfile varchar(64), @filename varchar(256)';

exec sp_executesql

@SQLCmd,

@params,

@dbname = @dbname,

@diskfile = @diskfile,

@filename = @filename;