ORA-16086: Redo data cannot be written to the standby redo log

The primary database is operating in MAXIMUM PROTECTION
or MAXIMUM AVAILABILITY mode, and the standby database does
not contain any viable standby redo logfiles.
ORA-16086: Redo data cannot be written to the standby redo log

Cause of the Problem
The problem happened due to recovery area of standby database becomes full and standby redo logs have no place for archival. As the standby redo logs can’t be archived, so they can’t free space in order to accommodate/write new logs.

Solution of the Problem Increase the recovery area size of standby database. You can check the location of archived redo log file by,

SQL> connect / as sysdba
SQL> archive log list

If you see that archive destination is USE_DB_RECOVERY_FILE_DEST then the location will be specified by parameter DB_RECOVERY_FILE_DEST.

SQL> SHOW PARAMETER DB_RECOVERY_FILE_DEST
+RECOVERY

Note that you have sufficient storage under +RECOVERY and also you have set proper size of the parameter db_recovery_file_dest_size.

To check the size of parameter db_recovery_file_dest_size issue,

SQL> show parameter db_recovery_file_dest_size

In order to increase the size of db_recovery_file_dest_size parameter issue,

SQL> alter system set db_recovery_file_dest_size = 1000G scope=both sid='*';