Greetings.
I recieved this error when attempting to restart SQL Server 2008R2 after installing SP2. The install claimed it was successful upon completion, but then wouldn't restart.
There are many posts similar to this one, but very few having this precise error number of 3906, and those don't really explain what the solution is (at least that I've found).
I queried the messages view:
Select * from sys.messages where message_id = 3906
And the message is:
"Failed to update database "%.*ls" because the database is read-only."
This is odd, as there are no read-only DB's on this instance. There is however a mirror in suspened/ restoring state. I suspect this may be related, but would like some insight before re-attempting.
Another fun fact is that I did this on another instance at the same time. That instance really does have a read-only DB.
Thanks!
TIA, ChrisRDBA