Thank you, Paul. But I was single user at that time. By the way, is it
possible to get list of database objects, modified after specified date?

Paul Reeves wrote:

>There is no such thing as single-user mode. Shutdown only stops
>non-SYSDBA attachments. When a database has been shut-down SYSDBA is
>still allowed to open an unlimited number of connections. Presumably the
>engine is still caching metadata from previous connections, hence the error.
>
>You need to stop the server and then connect as SYSDBA to make this kind
>of change.
>
>
>Paul
>
>