ERROR: ORA-00257: archiver error. Connect internal only, until freed.

This is due to FRA getting full.

Find the usage by using below query

col ROUND(SPACE_LIMIT/1048576) heading “Space Allocated (MB)” format 999999
col round(space_used/1048576) heading “Space Used (MB)” format 99999
col name format a40
select name, round(space_limit/1048576) As space_limit,round(space_used/1048576) As space_used
from v$RECOVERY_FILE_DEST;

After that please remove the archive or flash back logs to free up space.

delete archivelog until time 'SYSDATE-1';

Or decrease and increase the FRA size to remove flashback logs.

Or increase the FRA to free the archiver from errors.