Hi,

We had exactly same issue this morning, autoclose option is disabled on DB settings.

But we had san outage (1min) which caused network drive disruptions on the server, so the SQL server couldn't find one of the database log other user db are fine just one impacted.

After taking offline/online resolved this issue, I think taking offline would have reconnected the log paths in sql system database!! this my guess.

May be SQL experts could throw some info on what happen when you take offline with in the SQL server. Or what happen to the log data?

Environment is - virtual on SQL Microsoft SQL Server 2008 R2 (SP3) - 10.50.6220.0 (X64) Mar 19 2015 12:32:14 Copyright (c) Microsoft Corporation Standard Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1) (Hypervisor)