Hi there PalimPalim,
Another post with a similar issue was posted not long ago:
http://forums.pimoroni.com/t/skywriter-hat-issue-an-invalid-gestiic-library-was-stored-or-the-last-update-failed/5100?u=raspberrypicardbox
Gadgetoid suggested some ways of fixing the issue, but I don’t believe the cause was ever decidedly found. Perhaps try what is suggested there and log your results back here?
Thanks,
-Picard