On Physical Standby Data Guard, Following command failed with ORA-01182. Error itself self explanatory.
As a part of solution, you just need to End up recovery sessions and bounce back your database to Mount mode and issue SQL command again.

Error Log:

SQL> alter database create datafile '/u01/app/oracle/product/11.2.0/prod/dbs/UNNAMED00100' as '/u03/Oradata/Prod_OTHER_0072.DAT';
alter database create datafile '/u01/app/oracle/product/11.2.0/prod/dbs/UNNAMED00100' as '/u03/Oradata/Prod_OTHER_0072.DAT'
*
ERROR at line 1:
ORA-01182: cannot create database file 10 - file is in use or recovery
ORA-01111: name for data file 10 is unknown - rename to correct file
ORA-01110: data file 10:
'/u01/app/oracle/product/11.2.0/prod/dbs/UNNAMED00100'

You just can’t create a datafile that already being online or is being recovered.

Solution:

SQL> shutdown immediate;

SQL> startup mount;

SQL>  < Issue above SQL Command >;

 

Thanks,

Stay Tune. 🙂