I upgraded a cluster from 8.3 to 8.4. Things seemed to be fine so I dropped the 8.3 cluster. Then noticed an error and found that the archive_command was still pointing to the 8.3 data directory
archive_command = 'cp "%p" /var/lib/postgresql/8.3/main/wal_archives/"%f"'
I changed this to 8.4 but now continually get the following errors in the log file and process list for one specific file
2014-10-09 17:02:12 CDT DETAIL: The failed archive command was: cp "pg_xlog/000000010000000000000012" /var/lib/postgresql/8.4/main/wal_archives/"000000010000000000000012"
cp: cannot create regular file `/var/lib/postgresql/8.4/main/wal_archives/000000010000000000000012': No such file or directory
4122 ? Ss 0:00 \_ postgres: archiver process failed on 000000010000000000000012
I'm not sure the best way to recover from this. As far as I can tell the database is fully functional