When you connect RMAN to the source database as TARGET you must specify a password even if RMAN uses operating system authentication.
So the errors ORA-17627 and ORA-00942 appear to be cause and effect.
What version of Oracle? ( 184.108.40.206 according to the tag )
Can you post your backup script?
According to :
Database Error Messages 11g Release 2 (11.2) E17766-03
RMAN-06820: WARNING: failed to archive current log at primary database
Cause: An attempt to switch the archived log at the primary database failed.
So I would check my Primary alert log for an issue.
Message was edited by: mseberg