ORA-16434: Archive log for branch string thread string sequence string cannot be queued.
Cause: An archive log needed by the standby database to resolve a redo gap was not found on the primary database. This is a fatal situation during a switchover because the primary database waits for the target standby to be clear of all archive log gaps before allowing the switchover to proceed. If a redo gap cannot be resolved, the switchover cannot succeed.
Action: If the specified log is listed in V$ARCHIVED_LOG for the DEST_ID of the local destination on the primary database but no longer exists in that location on disk, the archived log can be copied back to that location to allow gap processing to automatically resolve the gap. If the specified log has been purged from V$ARCHIVED_LOG, the archived log can be copied to disk on either the primary or standby database and registered using the ALTER DATABASE REGISTER OR REPLACE LOGFILE command.
ORA-16434: Archive log for branch string thread string sequence string cannot be queued.
ORA-16434 出现时指示尝试更新被同步副本的 ARC（即archived log）日志记录时发生错误。
这个错误通常发生在当某一被同步副本的日志记录未能存档就加入了队列时。
1.开启审计功能以查看正在进行的任务，以及问题是与哪个任务相关。
2.查看数据库服务器错误日志以获取更详细的错误信息。
3.检查同步副本的 ARC（即archived log）是否可用。
4.检查队列的情况，以确认其中是否有足够的空间可以支持存档日志记录的更新。
5.检查 ARC 配置，以确认在队列中的 ARC 空间是否足够。
6.检查队列的位置，以确认存档日志记录能否被正确更新到其中。
7.如果以上排查都没有查出问题，请尝试重启数据库服务器，以避免该错误的出现，同时查看错误是否消失，或者出现在其他日志记录的更新过程中。