Ora-19838 -- restore control files to the standby database

oerr ora 19838
19838, 00000, "Cannot use this control file to open database"
// *Cause: This control file was restored by a DUPLICATE operation used only
//         to restore and recover the datafiles of the new database.  It is
//         not meant to be used for opening the database, as allowing so
//         might corrupt datafiles or online redo logs of the target 
//         database or both.
// *Action: Re-create control file manually specifying all names of datafiles
//          and online redo logs.  Do not forget to use NID to change the
//          name or DBID or both of the new database.

Main database backup

backup current controlfile for standby format 'stdbyctl.bkp';

list backup of controlfile;

Backup recovery

restore standby controlfile from 'stdbyctl.bkp';
catalog start with '/data/datafile/';
switch database to copy;

select name from v$datafile;