This is the message I get when I try topic.twitter.com/cSZCh4lr91
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
@TeamYouTube hi!! Is the feature to update channel banners currently down? For some reason I can’t update mine 

Hey there! Appreciate that you've brought this to our attention. Updating channel art can be done using a computer: https://yt.be/help/sg6D . If you're still having trouble, point us in the right direction by sending a screenshot of any error seen. Keep us posted.
This is the error message that I’ve been getting all day. I’ve never had an issue beforepic.twitter.com/h7OajowrUQ
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.