Try the statement later?

I got an error message I’d never seen before while altering a database.

Database is in transition. Try the statement later. (Microsoft SQL Server, Error: 952)

Try the statement later? What does that mean? I altered a column in a test database and immediately tried to take it offline. That is when I got the error. After searching for the message I found this. One of the solutions suggested was to search sys.dm_exec_requests for an alter process on that database. Sure enough it was suspended. I killed the SPID and the database was back online pretty quickly.