Pushed this change to this forum, the notification will go away if you scroll down or after 10 seconds, and it only shows up if the topic has more than 10 posts.
Thanks for reporting as @pkiller mentioned this should be fixed if you create the system folder. I have also fixed it on master as well as the error messages so you should get a better error message if the upload fails.
@julian Glad to hear that it is working again.
You can see the version next to the extension title:
chrome://extensions/?id=ooeikplgcjeeggiopajfhmadglhjhcco