ORA-19838: Cannot use this control file to open database

This error would come if you are trying to open a database with reset logs after you performed database duplication using DUPLICATE command, but duplicate command failed, and you completed rest of the steps manually. If duplicate command fails in the middle because of some issue, you can solve that issue and resume duplicate command. However, if you plan not to resume duplicate command and perform rest of the steps manually, you would need to recreate controlfile before you can open the database using RESETLOGS.