I am unable to login because the site http://ai2.appinventor.mit.edu/ is not loading since yesterday ie 01/08/2020. It shows error message time out.
That same Error page tells you what to do!
However, the cause might be a glitch in your Broadband, or maybe another User is using-up the broadband width. Do not have upteen other websites running in your Browser.
Ultimately, a PC reboot should fix the issue.
You have probably waiting until the tab loads to sign in with google and you have gonna to other tab in your browser and the session has timed out. It is less than 1 minute that we have to click on our google account and input password.
I think issue from your internet connection ..
I get the same issue,if have little bar network of internet connection..
try connect appinvenyor if have best internet connection or use appinventor offline.