Hoy vamos a volver con una entrada rapida de un problema muy facil de solucionar.

A veces, podemos encnontrarnos en el alert.log con el error

ORA-38870:cannot backup a control file that may have incorrect data file structure

Si miramos las trazas asustan bastante

2018-10-23T16:08:43.542081+02:00
Errors in file /u01/app/oracle/diag/rdbms/test_stby/test/trace/test_m000_425.trc:
ORA-38870: cannot backup a control file that may have incorrect data file structure.
2018-10-23T16:13:43.189251+02:00
Starting control autobackup
********************  WARNING ***************************
The errors during Server autobackup are not fatal, as it
is attempted after sucessful completion of the command.
However, it is recomended to take an RMAN control file
backup as soon as possible because the Autobackup failed
with the following error:
ORA-38870: cannot backup a control file that may have incorrect data file structure.
********************  END OF WARNING *******************

Pero, buscando en la documentacion de Oracle, nos contraremos que

Error code: ORA-38870

Description: cannot backup a control file that may have incorrect data file structure.
This control file was created or converted based on a control file from a time different from the time of the database.
Action: Open database read-only to synchronize the control file with the database dictionary to fix the control file

Cualquier cosa relaccionada con una estructura invalida de un controlfile puede asustar bastante, pero , este alarmante problema se soluciona de manera muy rapida y sencilla, simplemente haciendo eso, abriendo la base de datos en modo lectura.
Y ya no volveremos a ver mas el problema