The typical reason for this is that the Postng journal data file was deleted, rather than using the program to print and purge the file. There is a setting in the Company Profile to keep track of which postnig sequences have been printed and purged, and based on what you reported, there is a single sequence that the program is expecting to find but for some reason cannot - likely because the file was removed.

The solution is to either restore that removed (renamed) APPOSTR data file so that you can purge everything (then remove it again so that it comes back into synch with the Company Profile), or get a database repair.