Cause: Failed to either make a tablespace read-only or offline because it is not online. A tblespace must be online before it can become read-only or offline normal. See the solution below.
Error solution: Check the status of the tablespace. Use IMMEDIATE or TEMPORARY options to force all files offline. Bring the tablespace online before making it read-only.
Database version: Oracle 11g Release 2 (11.2)