I just noticed that my app, Steemit Benefactors was not letting me sign in. It is now back up after a small outage due to the steemconnect URLs changing from v2.steemconnect.com to steemconnect.com, this issue has been promptly fixed and the app is now working.
It seems that @dmania are also suffering from this issue and have not yet fixed it.
Big thanks to @certseek for fixing the issue! - Check out his awesome @dlike app!