ALTER DATABASE failed because a lock could not be placed on database

Try this if it is "in transition" ...

http://learnmysql.blogspot.com/2012/05/database-is-in-transition-try-statement.html

USE master
GO

ALTER DATABASE <db_name>

SET OFFLINE WITH ROLLBACK IMMEDIATE
...
...
ALTER DATABASE <db_name> SET ONLINE

After you get the error, run

EXEC sp_who2

Look for the database in the list. It's possible that a connection was not terminated. If you find any connections to the database, run

KILL <SPID>

where <SPID> is the SPID for the sessions that are connected to the database.

Try your script after all connections to the database are removed.

Unfortunately, I don't have a reason why you're seeing the problem, but here is a link that shows that the problem has occurred elsewhere.

http://www.geakeit.co.uk/2010/12/11/sql-take-offline-fails-alter-database-failed-because-a-lock-could-not-error-5061/

I managed to reproduce this error by doing the following.

Connection 1 (leave running for a couple of minutes)

CREATE DATABASE TESTING123
GO

USE TESTING123;

SELECT NEWID() AS X INTO FOO
FROM sys.objects s1,sys.objects s2,sys.objects s3,sys.objects s4 ,sys.objects s5 ,sys.objects s6

Connections 2 and 3

set lock_timeout 5;

ALTER DATABASE TESTING123 SET SINGLE_USER WITH ROLLBACK IMMEDIATE;