This means that your standby db is still not in sync with the primary.

In what point of time your archive logs have been appied to your standby?

If the proble with regards to datafile is still exist I don't think you have applied successfully the archive logs after the timestamp where in datafile was created.

Take a look in the alert log of your standby database, and try to find if there is a ORA-600 errors.

Observe also how log switching happens in your Primary database, if there is a fast switching, your standby db most probably didn't able to keep up with the primary db resulting this type of error.