Which SQL Server 2008 message is spelled correctly?
They're both technically correct spelling.
http://www.merriam-webster.com/dictionary/canceled
Both are acceptable according to: Merriam-Webster, dictionary.com, Google Dictionary
Cancelled is the correct way to spell it (or at least the most popular one), although canceled is, albeit partially, somewhat accepted. My recommendation is to always use cancelled.
They're both technically correct spelling.
http://www.merriam-webster.com/dictionary/canceled