well, the only time I've seen that is a pkg with unique characters like the trademark symbol. the wii u does the same thing.if it's happening with all pkgs, yeah, reinstall the firmware.
Thank you for the hint. However the problem isn't that in this case.
I re-installed the HFW (4.84.2), initialized HAN from the xploit page and the Package Manger has returned to work.
The update package have been installed without problems.