Tutorials not loading

Getting a error message that this page is not working - appinventor.mit.edu didn't send any data. ERR_EMPTY_RESPONSE

PDFs not working:

appinventor.mit.edu/explore/sites/all/files/hourofcode/TalkToMePart1

appinventor.mit.edu/explore/sites/all/files/hourofcode/TalkToMePart2

appinventor.mit.edu/explore/sites/all/files/hourofcode/BallBounceTutorial

/appinventor.mit.edu/explore/sites/all/files/hourofcode/DigitalDoodle

Tutorials not loading left sidebar properly:

Hour of Code
Ball Bounce
Digital Doodle

We are looking into it. Note that the sidebar tutorials are hosted on mit-cml.github.io, so if you are in a school environment please make sure that domain is also accessible.

Thank you, I did confirm that we have mit-cml.github.io whitelisted.